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// Copyright 2020 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "src/tint/lang/wgsl/reader/parser/parser.h"
#include <limits>
#include <utility>
#include "src/tint/lang/core/attribute.h"
#include "src/tint/lang/core/type/depth_texture.h"
#include "src/tint/lang/core/type/external_texture.h"
#include "src/tint/lang/core/type/multisampled_texture.h"
#include "src/tint/lang/core/type/sampled_texture.h"
#include "src/tint/lang/core/type/texture_dimension.h"
#include "src/tint/lang/wgsl/ast/assignment_statement.h"
#include "src/tint/lang/wgsl/ast/break_if_statement.h"
#include "src/tint/lang/wgsl/ast/break_statement.h"
#include "src/tint/lang/wgsl/ast/call_statement.h"
#include "src/tint/lang/wgsl/ast/continue_statement.h"
#include "src/tint/lang/wgsl/ast/discard_statement.h"
#include "src/tint/lang/wgsl/ast/id_attribute.h"
#include "src/tint/lang/wgsl/ast/if_statement.h"
#include "src/tint/lang/wgsl/ast/increment_decrement_statement.h"
#include "src/tint/lang/wgsl/ast/input_attachment_index_attribute.h"
#include "src/tint/lang/wgsl/ast/invariant_attribute.h"
#include "src/tint/lang/wgsl/ast/loop_statement.h"
#include "src/tint/lang/wgsl/ast/return_statement.h"
#include "src/tint/lang/wgsl/ast/stage_attribute.h"
#include "src/tint/lang/wgsl/ast/switch_statement.h"
#include "src/tint/lang/wgsl/ast/unary_op_expression.h"
#include "src/tint/lang/wgsl/ast/var.h"
#include "src/tint/lang/wgsl/ast/variable_decl_statement.h"
#include "src/tint/lang/wgsl/ast/workgroup_attribute.h"
#include "src/tint/lang/wgsl/reader/parser/classify_template_args.h"
#include "src/tint/lang/wgsl/reader/parser/lexer.h"
#include "src/tint/utils/containers/reverse.h"
#include "src/tint/utils/macros/defer.h"
#include "src/tint/utils/text/string.h"
#include "src/tint/utils/text/string_stream.h"
namespace tint::wgsl::reader {
namespace {
using Void = Parser::Void;
/// An instance of Void that can be used to signal success for functions that return Expect<Void> or
/// Maybe<NoError>.
static constexpr Void kSuccess;
template <typename T>
using Expect = Parser::Expect<T>;
template <typename T>
using Maybe = Parser::Maybe<T>;
/// Controls the maximum number of times we'll call into the sync() and
/// unary_expression() functions from themselves. This is to guard against stack
/// overflow when there is an excessive number of blocks.
constexpr uint32_t kMaxParseDepth = 128;
/// The maximum number of tokens to look ahead to try and sync the
/// parser on error.
constexpr size_t const kMaxResynchronizeLookahead = 32;
// https://gpuweb.github.io/gpuweb/wgsl.html#reserved-keywords
//
// Must be called with an identifier token.
bool is_reserved(const Token& t) {
auto s = t.to_str_view();
return s == "NULL" || s == "Self" || s == "abstract" || s == "active" || s == "alignas" ||
s == "alignof" || s == "as" || s == "asm" || s == "asm_fragment" || s == "async" ||
s == "attribute" || s == "auto" || s == "await" || s == "become" ||
s == "binding_array" || s == "cast" || s == "catch" || s == "class" || s == "co_await" ||
s == "co_return" || s == "co_yield" || s == "coherent" || s == "column_major" ||
s == "common" || s == "compile" || s == "compile_fragment" || s == "concept" ||
s == "const_cast" || s == "consteval" || s == "constexpr" || s == "constinit" ||
s == "crate" || s == "debugger" || s == "decltype" || s == "delete" || s == "demote" ||
s == "demote_to_helper" || s == "do" || s == "dynamic_cast" || s == "enum" ||
s == "explicit" || s == "export" || s == "extends" || s == "extern" || s == "external" ||
s == "filter" || s == "final" || s == "finally" || s == "friend" || s == "from" ||
s == "fxgroup" || s == "get" || s == "goto" || s == "groupshared" || s == "highp" ||
s == "impl" || s == "implements" || s == "import" || s == "inline" ||
s == "instanceof" || s == "interface" || s == "layout" || s == "lowp" || s == "macro" ||
s == "macro_rules" || s == "match" || s == "mediump" || s == "meta" || s == "mod" ||
s == "module" || s == "move" || s == "mut" || s == "mutable" || s == "namespace" ||
s == "new" || s == "nil" || s == "noexcept" || s == "noinline" ||
s == "nointerpolation" || s == "noperspective" || s == "null" || s == "nullptr" ||
s == "of" || s == "operator" || s == "package" || s == "packoffset" ||
s == "partition" || s == "pass" || s == "patch" || s == "pixelfragment" ||
s == "precise" || s == "precision" || s == "premerge" || s == "priv" ||
s == "protected" || s == "pub" || s == "public" || s == "readonly" || s == "ref" ||
s == "regardless" || s == "register" || s == "reinterpret_cast" || s == "require" ||
s == "resource" || s == "restrict" || s == "self" || s == "set" || s == "shared" ||
s == "sizeof" || s == "smooth" || s == "snorm" || s == "static" ||
s == "static_assert" || s == "static_cast" || s == "std" || s == "subroutine" ||
s == "super" || s == "target" || s == "template" || s == "this" || s == "thread_local" ||
s == "throw" || s == "trait" || s == "try" || s == "type" || s == "typedef" ||
s == "typeid" || s == "typename" || s == "typeof" || s == "union" || s == "unless" ||
s == "unorm" || s == "unsafe" || s == "unsized" || s == "use" || s == "using" ||
s == "varying" || s == "virtual" || s == "volatile" || s == "wgsl" || s == "where" ||
s == "with" || s == "writeonly" || s == "yield";
}
/// Enter-exit counters for block token types.
/// Used by sync_to() to skip over closing block tokens that were opened during
/// the forward scan.
struct BlockCounters {
int brace = 0; // { }
int bracket = 0; // [ ]
int paren = 0; // ( )
/// @return the current enter-exit depth for the given block token type. If
/// `t` is not a block token type, then 0 is always returned.
int consume(const Token& t) {
if (t.Is(Token::Type::kBraceLeft)) {
return brace++;
}
if (t.Is(Token::Type::kBraceRight)) {
return brace--;
}
if (t.Is(Token::Type::kBracketLeft)) {
return bracket++;
}
if (t.Is(Token::Type::kBracketRight)) {
return bracket--;
}
if (t.Is(Token::Type::kParenLeft)) {
return paren++;
}
if (t.Is(Token::Type::kParenRight)) {
return paren--;
}
return 0;
}
};
} // namespace
/// RAII helper that combines a Source on construction with the last token's
/// source when implicitly converted to `Source`.
class Parser::MultiTokenSource {
public:
/// Constructor that starts with Source at the current peek position
/// @param parser the parser
explicit MultiTokenSource(Parser* parser)
: MultiTokenSource(parser, parser->peek().source().Begin()) {}
/// Constructor that starts with the input `start` Source
/// @param parser the parser
/// @param start the start source of the range
MultiTokenSource(Parser* parser, const tint::Source& start) : parser_(parser), start_(start) {}
/// @returns the Source that returns the combined source from start to the current last token's
/// source.
tint::Source operator()() const { return *this; }
/// @returns the Source that returns the combined source from start to the current last token's
/// source.
operator tint::Source() const {
auto end = parser_->last_source().End();
if (end < start_) {
end = start_;
}
return Source::Combine(start_, end);
}
private:
Parser* parser_;
tint::Source start_;
};
Parser::TypedIdentifier::TypedIdentifier() = default;
Parser::TypedIdentifier::TypedIdentifier(const TypedIdentifier&) = default;
Parser::TypedIdentifier::TypedIdentifier(ast::Type type_in, const ast::Identifier* name_in)
: type(type_in), name(name_in) {}
Parser::TypedIdentifier::~TypedIdentifier() = default;
Parser::FunctionHeader::FunctionHeader() = default;
Parser::FunctionHeader::FunctionHeader(const FunctionHeader&) = default;
Parser::FunctionHeader::FunctionHeader(Source src,
const ast::Identifier* n,
VectorRef<const ast::Parameter*> p,
ast::Type ret_ty,
VectorRef<const ast::Attribute*> ret_attrs)
: source(src),
name(n),
params(std::move(p)),
return_type(ret_ty),
return_type_attributes(std::move(ret_attrs)) {}
Parser::FunctionHeader::~FunctionHeader() = default;
Parser::FunctionHeader& Parser::FunctionHeader::operator=(const FunctionHeader& rhs) = default;
Parser::Parser(Source::File const* file) : file_(file) {}
Parser::~Parser() = default;
Parser::Failure::Errored Parser::AddError(const Source& source,
std::string_view err,
std::string_view use) {
if (silence_diags_ == 0) {
StringStream msg;
msg << err;
if (!use.empty()) {
msg << " for " << use;
}
AddError(source, msg.str());
}
return Failure::kErrored;
}
Parser::Failure::Errored Parser::AddError(const Token& t, std::string_view err) {
AddError(t.source(), err);
return Failure::kErrored;
}
Parser::Failure::Errored Parser::AddError(const Source& source, std::string_view err) {
if (silence_diags_ == 0) {
builder_.Diagnostics().AddError(source) << err;
}
return Failure::kErrored;
}
Parser::Failure::Errored Parser::AddError(const Source& source, StyledText&& err) {
if (silence_diags_ == 0) {
builder_.Diagnostics().AddError(source) << std::move(err);
}
return Failure::kErrored;
}
void Parser::AddNote(const Source& source, std::string_view err) {
if (silence_diags_ == 0) {
builder_.Diagnostics().AddNote(source) << err;
}
}
void Parser::deprecated(const Source& source, std::string_view msg) {
if (silence_diags_ == 0) {
builder_.Diagnostics().AddWarning(source) << "use of deprecated language feature: " << msg;
}
}
const Token& Parser::next() {
// If the next token is already an error or the end of file, stay there.
if (tokens_[next_token_idx_].IsEof() || tokens_[next_token_idx_].IsError()) {
return tokens_[next_token_idx_];
}
// Skip over any placeholder elements
while (true) {
if (!tokens_[next_token_idx_].IsPlaceholder()) {
break;
}
next_token_idx_++;
}
last_source_idx_ = next_token_idx_;
if (!tokens_[next_token_idx_].IsEof() && !tokens_[next_token_idx_].IsError()) {
next_token_idx_++;
}
return tokens_[last_source_idx_];
}
const Token& Parser::peek(size_t count) {
for (size_t idx = next_token_idx_; idx < tokens_.size(); idx++) {
if (tokens_[idx].IsPlaceholder()) {
continue;
}
if (count == 0) {
return tokens_[idx];
}
count--;
}
// Walked off the end of the token list, return last token.
return tokens_[tokens_.size() - 1];
}
bool Parser::peek_is(Token::Type tok, size_t idx) {
return peek(idx).Is(tok);
}
void Parser::split_token(Token::Type lhs, Token::Type rhs) {
if (TINT_UNLIKELY(next_token_idx_ == 0)) {
TINT_ICE() << "attempt to update placeholder at beginning of tokens";
}
if (TINT_UNLIKELY(next_token_idx_ >= tokens_.size())) {
TINT_ICE() << "attempt to update placeholder past end of tokens";
}
if (TINT_UNLIKELY(!tokens_[next_token_idx_].IsPlaceholder())) {
TINT_ICE() << "attempt to update non-placeholder token";
}
tokens_[next_token_idx_ - 1].SetType(lhs);
tokens_[next_token_idx_].SetType(rhs);
}
Source Parser::last_source() const {
return tokens_[last_source_idx_].source();
}
void Parser::InitializeLex() {
Lexer l{file_};
tokens_ = l.Lex();
ClassifyTemplateArguments(tokens_);
}
bool Parser::Parse() {
InitializeLex();
translation_unit();
return !has_error();
}
// translation_unit
// : global_directive* global_decl* EOF
void Parser::translation_unit() {
bool after_global_decl = false;
while (continue_parsing()) {
auto& p = peek();
if (p.IsEof()) {
break;
}
auto ed = global_directive(after_global_decl);
if (!ed.matched && !ed.errored) {
auto gd = global_decl();
if (gd.matched) {
after_global_decl = true;
}
if (!gd.matched && !gd.errored) {
AddError(p, "unexpected token");
}
}
if (builder_.Diagnostics().NumErrors() >= max_errors_) {
AddError(Source{{}, p.source().file},
"stopping after " + std::to_string(max_errors_) + " errors");
break;
}
}
}
// global_directive
// : diagnostic_directive
// | requires_directive
// | enable_directive
Maybe<Void> Parser::global_directive(bool have_parsed_decl) {
auto& p = peek();
Maybe<Void> result = diagnostic_directive();
if (!result.errored && !result.matched) {
result = enable_directive();
}
if (!result.errored && !result.matched) {
result = requires_directive();
}
if (result.matched && have_parsed_decl) {
return AddError(p, "directives must come before all global declarations");
}
return result;
}
// diagnostic_directive
// : diagnostic diagnostic_control SEMICOLON
Maybe<Void> Parser::diagnostic_directive() {
auto decl = sync(Token::Type::kSemicolon, [&]() -> Maybe<Void> {
if (!match(Token::Type::kDiagnostic)) {
return Failure::kNoMatch;
}
auto source = last_source();
auto control = expect_diagnostic_control();
if (control.errored) {
return Failure::kErrored;
}
if (!expect("diagnostic directive", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
auto* directive = create<ast::DiagnosticDirective>(source, std::move(control.value));
builder_.AST().AddDiagnosticDirective(directive);
return kSuccess;
});
if (decl.errored) {
return Failure::kErrored;
}
return decl;
}
// enable_directive :
// | 'enable' identifier (COMMA identifier)* COMMA? SEMICOLON
Maybe<Void> Parser::enable_directive() {
return sync(Token::Type::kSemicolon, [&]() -> Maybe<Void> {
MultiTokenSource decl_source(this);
if (!match(Token::Type::kEnable)) {
return Failure::kNoMatch;
}
if (peek_is(Token::Type::kParenLeft)) {
// A common error case is writing `enable(foo);` instead of `enable foo;`.
synchronized_ = false;
return AddError(peek().source(), "enable directives don't take parenthesis");
}
Vector<const ast::Extension*, 4> extensions;
while (continue_parsing()) {
Source ext_src = peek().source();
auto ext = expect_enum("extension", wgsl::ParseExtension, wgsl::kExtensionStrings);
if (ext.errored) {
return Failure::kErrored;
}
extensions.Push(create<ast::Extension>(ext_src, ext.value));
if (!match(Token::Type::kComma)) {
break;
}
if (peek_is(Token::Type::kSemicolon)) {
break;
}
}
if (!expect("enable directive", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
builder_.AST().AddEnable(create<ast::Enable>(decl_source(), std::move(extensions)));
return kSuccess;
});
}
// requires_directive
// : require identifier (COMMA identifier)* COMMA? SEMICOLON
Maybe<Void> Parser::requires_directive() {
return sync(Token::Type::kSemicolon, [&]() -> Maybe<Void> {
MultiTokenSource decl_source(this);
if (!match(Token::Type::kRequires)) {
return Failure::kNoMatch;
}
// Match the require name.
auto& t = peek();
if (handle_error(t)) {
// The token might itself be an error.
return Failure::kErrored;
}
if (t.Is(Token::Type::kParenLeft)) {
// A common error case is writing `require(foo);` instead of `require foo;`.
synchronized_ = false;
return AddError(t.source(), "requires directives don't take parenthesis");
}
ast::Requires::LanguageFeatures features;
while (continue_parsing()) {
auto& t2 = next();
if (handle_error(t2)) {
// The token might itself be an error.
return Failure::kErrored;
}
// Match the require name.
if (t2.IsIdentifier()) {
auto feature = wgsl::ParseLanguageFeature(t2.to_str_view());
if (feature == LanguageFeature::kUndefined) {
// Any identifier is a valid feature name, so we correctly handle new feature
// names getting added in the future, they just all get flagged as not
// supported.
return AddError(t2.source(), "feature '" + t2.to_str() + "' is not supported");
}
features.Add(feature);
} else {
return AddError(t2.source(), "invalid feature name for requires");
}
if (!match(Token::Type::kComma)) {
break;
}
if (peek_is(Token::Type::kSemicolon)) {
break;
}
}
if (!expect("requires directive", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
builder_.AST().AddRequires(create<ast::Requires>(decl_source(), std::move(features)));
return kSuccess;
});
}
// global_decl
// : SEMICOLON
// | global_variable_decl SEMICOLON
// | global_constant_decl SEMICOLON
// | type_alias_decl SEMICOLON
// | struct_decl
// | function_decl
// | const_assert_statement SEMICOLON
Maybe<Void> Parser::global_decl() {
if (match(Token::Type::kSemicolon) || match(Token::Type::kEOF)) {
return kSuccess;
}
bool errored = false;
auto attrs = attribute_list();
if (attrs.errored) {
errored = true;
}
if (!continue_parsing()) {
return Failure::kErrored;
}
auto decl = sync(Token::Type::kSemicolon, [&]() -> Maybe<Void> {
auto gv = global_variable_decl(attrs.value);
if (gv.errored) {
return Failure::kErrored;
}
if (gv.matched) {
if (!expect("variable declaration", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
builder_.AST().AddGlobalVariable(gv.value);
return kSuccess;
}
auto gc = global_constant_decl(attrs.value);
if (gc.errored) {
return Failure::kErrored;
}
if (gc.matched) {
// Avoid the cost of the string allocation for the common no-error case
if (!peek().Is(Token::Type::kSemicolon)) {
std::string kind = gc->Kind();
if (!expect("'" + kind + "' declaration", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
}
return kSuccess;
}
auto ta = type_alias_decl();
if (ta.errored) {
return Failure::kErrored;
}
if (ta.matched) {
if (!expect("type alias", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
builder_.AST().AddTypeDecl(ta.value);
return kSuccess;
}
auto assertion = const_assert_statement();
if (assertion.errored) {
return Failure::kErrored;
}
if (assertion.matched) {
builder_.AST().AddConstAssert(assertion.value);
if (!expect("const assertion declaration", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
return kSuccess;
}
return Failure::kNoMatch;
});
if (decl.errored) {
errored = true;
}
if (decl.matched) {
if (expect_attributes_consumed(attrs.value).errored) {
return Failure::kErrored;
}
return kSuccess;
}
auto str = struct_decl();
if (str.errored) {
errored = true;
}
if (str.matched) {
if (expect_attributes_consumed(attrs.value).errored) {
return Failure::kErrored;
}
return kSuccess;
}
auto func = function_decl(attrs.value);
if (func.errored) {
errored = true;
}
if (func.matched) {
return kSuccess;
}
if (errored) {
return Failure::kErrored;
}
// Invalid syntax found - try and determine the best error message
// We have attributes parsed, but nothing to consume them?
if (attrs.value.Length() > 0) {
return AddError(next(), "expected declaration after attributes");
}
// We have a statement outside of a function?
auto& t = peek();
auto stat = without_diag([&] { return statement(); });
if (stat.matched) {
// Attempt to jump to the next '}' - the function might have just been
// missing an opening line.
sync_to(Token::Type::kBraceRight, true);
return AddError(t, "statement found outside of function body");
}
if (!stat.errored) {
// No match, no error - the parser might not have progressed.
// Ensure we always make _some_ forward progress.
next();
}
// The token might itself be an error.
if (handle_error(t)) {
return Failure::kErrored;
}
// Exhausted all attempts to make sense of where we're at.
// Return a no-match
return Failure::kNoMatch;
}
// global_variable_decl
// : variable_attribute_list* variable_decl (EQUAL expression)?
Maybe<const ast::Variable*> Parser::global_variable_decl(AttributeList& attrs) {
MultiTokenSource decl_source(this);
auto decl = variable_decl();
if (decl.errored) {
return Failure::kErrored;
}
if (!decl.matched) {
return Failure::kNoMatch;
}
const ast::Expression* initializer = nullptr;
if (match(Token::Type::kEqual)) {
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(peek(), "missing initializer for 'var' declaration");
}
initializer = expr.value;
}
TINT_DEFER(attrs.Clear());
return builder_.create<ast::Var>(decl_source(), // source
builder_.Ident(decl->name), // symbol
decl->type, // type
decl->address_space, // address space
decl->access, // access control
initializer, // initializer
std::move(attrs)); // attributes
}
// global_constant_decl :
// | LET optionally_typed_ident global_const_initializer
// | attribute* override optionally_typed_ident (equal expression)?
// global_const_initializer
// : EQUAL const_expr
Maybe<const ast::Variable*> Parser::global_constant_decl(AttributeList& attrs) {
bool is_overridable = false;
const char* use = nullptr;
MultiTokenSource decl_source(this);
Source source;
if (match(Token::Type::kConst)) {
use = "'const' declaration";
} else if (match(Token::Type::kOverride)) {
use = "'override' declaration";
is_overridable = true;
} else if (match(Token::Type::kLet, &source)) {
return AddError(source, "module-scope 'let' is invalid, use 'const'");
} else {
return Failure::kNoMatch;
}
auto decl = expect_optionally_typed_ident(use);
if (decl.errored) {
return Failure::kErrored;
}
bool has_initializer = false;
if (is_overridable) {
has_initializer = match(Token::Type::kEqual);
} else {
if (!expect(use, Token::Type::kEqual)) {
return Failure::kErrored;
}
has_initializer = true;
}
const ast::Expression* initializer = nullptr;
if (has_initializer) {
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(peek(), "missing initializer for " + std::string(use));
}
initializer = std::move(expr.value);
}
TINT_DEFER(attrs.Clear());
if (is_overridable) {
return builder_.Override(decl_source(), // source
decl->name, // symbol
decl->type, // type
initializer, // initializer
std::move(attrs)); // attributes
}
return builder_.GlobalConst(decl_source(), // source
decl->name, // symbol
decl->type, // type
initializer, // initializer
std::move(attrs)); // attributes
}
// variable_decl
// : VAR variable_qualifier? optionally_typed_ident
//
// Note, the `( LESS_THAN address_space ( COMMA access_mode )? GREATER_THAN ) is pulled out into
// a `variable_qualifier` helper.
Maybe<Parser::VarDeclInfo> Parser::variable_decl() {
Source source;
if (!match(Token::Type::kVar, &source)) {
return Failure::kNoMatch;
}
VariableQualifier vq;
auto explicit_vq = variable_qualifier();
if (explicit_vq.errored) {
return Failure::kErrored;
}
if (explicit_vq.matched) {
vq = explicit_vq.value;
}
auto decl = expect_optionally_typed_ident("variable declaration");
if (decl.errored) {
return Failure::kErrored;
}
return VarDeclInfo{decl->name->source, decl->name, vq.address_space, vq.access, decl->type};
}
Expect<Parser::TypedIdentifier> Parser::expect_ident_with_optional_type_specifier(
std::string_view use,
bool allow_inferred) {
auto ident = expect_ident(use);
if (ident.errored) {
return Failure::kErrored;
}
if (allow_inferred && !peek_is(Token::Type::kColon)) {
return TypedIdentifier{ast::Type{}, ident.value};
}
if (!expect(use, Token::Type::kColon)) {
return Failure::kErrored;
}
auto& t = peek();
auto type = type_specifier();
if (type.errored) {
return Failure::kErrored;
}
if (!type.matched) {
return AddError(t.source(), "invalid type", use);
}
return TypedIdentifier{type.value, ident.value};
}
// optionally_typed_ident
// : ident ( COLON typed_decl ) ?
Expect<Parser::TypedIdentifier> Parser::expect_optionally_typed_ident(std::string_view use) {
return expect_ident_with_optional_type_specifier(use, /* allow_inferred */ true);
}
// ident_with_type_specifier
// : IDENT COLON type_specifier
Expect<Parser::TypedIdentifier> Parser::expect_ident_with_type_specifier(std::string_view use) {
return expect_ident_with_optional_type_specifier(use, /* allow_inferred */ false);
}
// variable_qualifier
// : _template_args_start expression (COMMA expression)? _template_args_end
Maybe<Parser::VariableQualifier> Parser::variable_qualifier() {
if (!peek_is(Token::Type::kTemplateArgsLeft) && !peek_is(Token::Type::kLessThan)) {
// Note: kLessThan will give a sensible error at expect_template_arg_block()
return Failure::kNoMatch;
}
auto* use = "variable declaration";
auto vq = expect_template_arg_block(use, [&]() -> Expect<VariableQualifier> {
auto address_space = expect_expression("'var' address space");
if (address_space.errored) {
return Failure::kErrored;
}
if (match(Token::Type::kComma)) {
auto access = expect_expression("'var' access mode");
if (access.errored) {
return Failure::kErrored;
}
return VariableQualifier{address_space.value, access.value};
}
return VariableQualifier{address_space.value};
});
if (vq.errored) {
return Failure::kErrored;
}
return vq;
}
// type_alias_decl
// : ALIAS IDENT EQUAL type_specifier
Maybe<const ast::Alias*> Parser::type_alias_decl() {
MultiTokenSource source(this);
if (!match(Token::Type::kAlias)) {
return Failure::kNoMatch;
}
const char* use = "type alias";
auto name = expect_ident(use);
if (name.errored) {
return Failure::kErrored;
}
if (!expect(use, Token::Type::kEqual)) {
return Failure::kErrored;
}
auto type = type_specifier();
if (type.errored) {
return Failure::kErrored;
}
if (!type.matched) {
return AddError(peek(), "invalid type alias");
}
return builder_.ty.alias(source(), name.value, type.value);
}
// type_specifier
// : IDENTIFIER template_arguments?
Maybe<ast::Type> Parser::type_specifier() {
MultiTokenSource source(this);
auto& ident = peek();
if (!match(Token::Type::kIdentifier)) {
return Failure::kNoMatch;
}
if (!peek_is(Token::Type::kTemplateArgsLeft)) {
return builder_.ty(builder_.Ident(source(), ident.to_str()));
}
auto args = expect_template_arg_block("type template arguments", [&] {
return expect_expression_list("type template argument list",
Token::Type::kTemplateArgsRight);
});
if (args.errored) {
return Failure::kErrored;
}
return builder_.ty(builder_.Ident(source(), ident.to_str(), std::move(args.value)));
}
template <typename ENUM>
Expect<ENUM> Parser::expect_enum(std::string_view name,
ENUM (*parse)(std::string_view str),
Slice<const std::string_view> strings,
std::string_view use) {
auto& t = peek();
auto ident = t.to_str();
if (t.IsIdentifier()) {
auto val = parse(ident);
if (val != ENUM::kUndefined) {
synchronized_ = true;
next();
return val;
}
}
// Was the token itself an error?
if (handle_error(t)) {
return Failure::kErrored;
}
/// Create a sensible error message
StyledText err;
err << "expected " << name;
if (!use.empty()) {
err << " for " << use;
}
err << "\n";
if (strings == wgsl::kExtensionStrings && !HasPrefix(ident, "chromium")) {
// Filter out 'chromium' prefixed extensions. We don't want to advertise experimental
// extensions to end users (unless it looks like they've actually mis-typed a chromium
// extension name)
Vector<std::string_view, 8> filtered;
for (auto str : strings) {
if (!HasPrefix(str, "chromium")) {
filtered.Push(str);
}
}
tint::SuggestAlternatives(ident, filtered.Slice(), err);
} else {
tint::SuggestAlternatives(ident, strings, err);
}
synchronized_ = false;
return AddError(t.source(), std::move(err));
}
Expect<ast::Type> Parser::expect_type(std::string_view use) {
auto type = type_specifier();
if (type.errored) {
return Failure::kErrored;
}
if (!type.matched) {
return AddError(peek().source(), "invalid type", use);
}
return type.value;
}
// struct_decl
// : STRUCT IDENT struct_body_decl
Maybe<const ast::Struct*> Parser::struct_decl() {
MultiTokenSource source(this);
if (!match(Token::Type::kStruct)) {
return Failure::kNoMatch;
}
auto name = expect_ident("struct declaration");
if (name.errored) {
return Failure::kErrored;
}
auto body = expect_struct_body_decl();
if (body.errored) {
return Failure::kErrored;
}
return builder_.Structure(source(), name.value, std::move(body.value));
}
// struct_body_decl
// : BRACE_LEFT (struct_member COMMA)* struct_member COMMA? BRACE_RIGHT
Expect<Parser::StructMemberList> Parser::expect_struct_body_decl() {
return expect_brace_block("struct declaration", [&]() -> Expect<StructMemberList> {
StructMemberList members;
bool errored = false;
while (continue_parsing()) {
// Check for the end of the list.
auto& t = peek();
if (!t.IsIdentifier() && !t.Is(Token::Type::kAttr)) {
break;
}
auto member = expect_struct_member();
if (member.errored) {
errored = true;
if (!sync_to(Token::Type::kComma, /* consume: */ false)) {
return Failure::kErrored;
}
} else {
members.Push(member.value);
}
if (!match(Token::Type::kComma)) {
break;
}
}
if (errored) {
return Failure::kErrored;
}
return members;
});
}
// struct_member
// : attribute* ident_with_type_specifier
Expect<const ast::StructMember*> Parser::expect_struct_member() {
auto attrs = attribute_list();
if (attrs.errored) {
return Failure::kErrored;
}
auto decl = expect_ident_with_type_specifier("struct member");
if (decl.errored) {
return Failure::kErrored;
}
return builder_.Member(decl->name->source, decl->name, decl->type, std::move(attrs.value));
}
// const_assert_statement
// : STATIC_ASSERT expression
Maybe<const ast::ConstAssert*> Parser::const_assert_statement() {
MultiTokenSource source(this);
if (!match(Token::Type::kConstAssert)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return AddError(peek(), "unable to parse condition expression");
}
return create<ast::ConstAssert>(source(), condition.value);
}
// function_decl
// : function_header compound_statement
Maybe<const ast::Function*> Parser::function_decl(AttributeList& attrs) {
MultiTokenSource source(this);
auto header = function_header();
if (header.errored) {
if (sync_to(Token::Type::kBraceLeft, /* consume: */ false)) {
// There were errors in the function header, but the parser has managed to
// resynchronize with the opening brace. As there's no outer
// synchronization token for function declarations, attempt to parse the
// function body. The AST isn't used as we've already errored, but this
// catches any errors inside the body, and can help keep the parser in
// sync.
expect_compound_statement("function body");
}
return Failure::kErrored;
}
if (!header.matched) {
return Failure::kNoMatch;
}
bool errored = false;
auto body = expect_compound_statement("function body");
if (body.errored) {
errored = true;
}
if (errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return builder_.Func(source, header->name, header->params, header->return_type, body.value,
std::move(attrs), header->return_type_attributes);
}
// function_header
// : FN IDENT PAREN_LEFT param_list PAREN_RIGHT return_type_specifier_optional
// return_type_specifier_optional
// :
// | ARROW attribute_list* type_specifier
Maybe<Parser::FunctionHeader> Parser::function_header() {
Source source;
if (!match(Token::Type::kFn, &source)) {
return Failure::kNoMatch;
}
const char* use = "function declaration";
bool errored = false;
auto name = expect_ident(use);
if (name.errored) {
errored = true;
if (!sync_to(Token::Type::kParenLeft, /* consume: */ false)) {
return Failure::kErrored;
}
}
auto params = expect_paren_block(use, [&] { return expect_param_list(); });
if (params.errored) {
errored = true;
if (!synchronized_) {
return Failure::kErrored;
}
}
ast::Type return_type;
AttributeList return_attributes;
if (match(Token::Type::kArrow)) {
auto attrs = attribute_list();
if (attrs.errored) {
return Failure::kErrored;
}
return_attributes = attrs.value;
auto type = type_specifier();
if (type.errored) {
errored = true;
} else if (!type.matched) {
return AddError(peek(), "unable to determine function return type");
} else {
return_type = type.value;
}
} else {
return_type = builder_.ty.void_();
}
if (errored) {
return Failure::kErrored;
}
return FunctionHeader{
source, name.value, std::move(params.value), return_type, std::move(return_attributes),
};
}
// param_list
// :
// | (param COMMA)* param COMMA?
Expect<Parser::ParameterList> Parser::expect_param_list() {
ParameterList ret;
while (continue_parsing()) {
// Check for the end of the list.
auto& t = peek();
if (!t.IsIdentifier() && !t.Is(Token::Type::kAttr)) {
break;
}
auto param = expect_param();
if (param.errored) {
return Failure::kErrored;
}
ret.Push(param.value);
if (!match(Token::Type::kComma)) {
break;
}
}
return ret;
}
// param
// : attribute_list* ident COLON type_specifier
Expect<const ast::Parameter*> Parser::expect_param() {
auto attrs = attribute_list();
auto decl = expect_ident_with_type_specifier("parameter");
if (decl.errored) {
return Failure::kErrored;
}
return builder_.Param(decl->name->source, // source
decl->name, // symbol
decl->type, // type
std::move(attrs.value)); // attributes
}
// compound_statement
// : attribute* BRACE_LEFT statement* BRACE_RIGHT
Expect<ast::BlockStatement*> Parser::expect_compound_statement(std::string_view use) {
auto attrs = attribute_list();
if (attrs.errored) {
return Failure::kErrored;
}
return expect_compound_statement(attrs.value, use);
}
// compound_statement
// : attribute* BRACE_LEFT statement* BRACE_RIGHT
Expect<ast::BlockStatement*> Parser::expect_compound_statement(AttributeList& attrs,
std::string_view use) {
MultiTokenSource source(this);
auto stmts =
expect_brace_block(use, [&]() -> Expect<StatementList> { return expect_statements(); });
if (stmts.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::BlockStatement>(source(), stmts.value, std::move(attrs));
}
// paren_expression
// : PAREN_LEFT expression PAREN_RIGHT
Expect<const ast::Expression*> Parser::expect_paren_expression() {
return expect_paren_block("", [&]() -> Expect<const ast::Expression*> {
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(peek(), "unable to parse expression");
}
return expr.value;
});
}
// statements
// : statement*
Expect<Parser::StatementList> Parser::expect_statements() {
bool errored = false;
StatementList stmts;
while (continue_parsing()) {
auto stmt = statement();
if (stmt.errored) {
errored = true;
} else if (stmt.matched) {
stmts.Push(stmt.value);
} else {
break;
}
}
if (errored) {
return Failure::kErrored;
}
return stmts;
}
// statement
// : SEMICOLON
// | if_statement
// | switch_statement
// | loop_statement
// | for_statement
// | while_statement
// | compound_statement
// | non_block_statement // Note, we inject an extra rule in here for simpler parsing
Maybe<const ast::Statement*> Parser::statement() {
while (match(Token::Type::kSemicolon)) {
// Skip empty statements
}
auto attrs = attribute_list();
if (attrs.errored) {
return Failure::kErrored;
}
TINT_DEFER(expect_attributes_consumed(attrs.value));
// Non-block statements that error can resynchronize on semicolon.
auto stmt = sync(Token::Type::kSemicolon, [&] { return non_block_statement(); });
if (stmt.errored) {
return Failure::kErrored;
}
if (stmt.matched) {
return stmt;
}
auto stmt_if = if_statement(attrs.value);
if (stmt_if.errored) {
return Failure::kErrored;
}
if (stmt_if.matched) {
return stmt_if.value;
}
auto sw = switch_statement(attrs.value);
if (sw.errored) {
return Failure::kErrored;
}
if (sw.matched) {
return sw.value;
}
auto loop = loop_statement(attrs.value);
if (loop.errored) {
return Failure::kErrored;
}
if (loop.matched) {
return loop.value;
}
auto stmt_for = for_statement(attrs.value);
if (stmt_for.errored) {
return Failure::kErrored;
}
if (stmt_for.matched) {
return stmt_for.value;
}
auto stmt_while = while_statement(attrs.value);
if (stmt_while.errored) {
return Failure::kErrored;
}
if (stmt_while.matched) {
return stmt_while.value;
}
if (peek_is(Token::Type::kBraceLeft)) {
auto body = expect_compound_statement(attrs.value, "block statement");
if (body.errored) {
return Failure::kErrored;
}
return body.value;
}
return Failure::kNoMatch;
}
// non_block_statement (continued)
// : return_statement SEMICOLON
// | func_call_statement SEMICOLON
// | variable_statement SEMICOLON
// | break_statement SEMICOLON
// | continue_statement SEMICOLON
// | DISCARD SEMICOLON
// | variable_updating_statement SEMICOLON
// | const_assert_statement SEMICOLON
Maybe<const ast::Statement*> Parser::non_block_statement() {
auto stmt = [&]() -> Maybe<const ast::Statement*> {
auto ret_stmt = return_statement();
if (ret_stmt.errored) {
return Failure::kErrored;
}
if (ret_stmt.matched) {
return ret_stmt.value;
}
auto func = func_call_statement();
if (func.errored) {
return Failure::kErrored;
}
if (func.matched) {
return func.value;
}
auto var = variable_statement();
if (var.errored) {
return Failure::kErrored;
}
if (var.matched) {
return var.value;
}
auto b = break_statement();
if (b.errored) {
return Failure::kErrored;
}
if (b.matched) {
return b.value;
}
auto cont = continue_statement();
if (cont.errored) {
return Failure::kErrored;
}
if (cont.matched) {
return cont.value;
}
Source source;
if (match(Token::Type::kDiscard, &source)) {
return builder_.Discard(source);
}
// Note, this covers assignment, increment and decrement
auto assign = variable_updating_statement();
if (assign.errored) {
return Failure::kErrored;
}
if (assign.matched) {
return assign.value;
}
auto stmt_static_assert = const_assert_statement();
if (stmt_static_assert.errored) {
return Failure::kErrored;
}
if (stmt_static_assert.matched) {
return stmt_static_assert.value;
}
return Failure::kNoMatch;
}();
if (stmt.matched && !expect(stmt->Name(), Token::Type::kSemicolon)) {
return Failure::kErrored;
}
return stmt;
}
// return_statement
// : RETURN expression?
Maybe<const ast::ReturnStatement*> Parser::return_statement() {
Source source;
if (!match(Token::Type::kReturn, &source)) {
return Failure::kNoMatch;
}
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
return expr.matched ? builder_.Return(source, expr.value) : builder_.Return(source);
}
// variable_statement
// : variable_decl
// | variable_decl EQUAL expression
// | LET optionally_typed_ident EQUAL expression
// | CONST optionally_typed_ident EQUAL expression
Maybe<const ast::VariableDeclStatement*> Parser::variable_statement() {
MultiTokenSource decl_source_range(this);
if (match(Token::Type::kConst)) {
auto typed_ident = expect_optionally_typed_ident("'const' declaration");
if (typed_ident.errored) {
return Failure::kErrored;
}
auto decl_source = decl_source_range();
if (!expect("'const' declaration", Token::Type::kEqual)) {
return Failure::kErrored;
}
auto initializer = expression();
if (initializer.errored) {
return Failure::kErrored;
}
if (!initializer.matched) {
return AddError(peek(), "missing initializer for 'const' declaration");
}
auto* const_ = builder_.Const(typed_ident->name->source, // source
typed_ident->name, // symbol
typed_ident->type, // type
initializer.value); // initializer
return create<ast::VariableDeclStatement>(decl_source, const_);
}
if (match(Token::Type::kLet)) {
auto typed_ident = expect_optionally_typed_ident("'let' declaration");
if (typed_ident.errored) {
return Failure::kErrored;
}
auto decl_source = decl_source_range();
if (!expect("'let' declaration", Token::Type::kEqual)) {
return Failure::kErrored;
}
auto initializer = expression();
if (initializer.errored) {
return Failure::kErrored;
}
if (!initializer.matched) {
return AddError(peek(), "missing initializer for 'let' declaration");
}
auto* let = builder_.Let(typed_ident->name->source, // source
typed_ident->name, // symbol
typed_ident->type, // type
initializer.value); // initializer
return create<ast::VariableDeclStatement>(decl_source, let);
}
auto decl = variable_decl();
if (decl.errored) {
return Failure::kErrored;
}
if (!decl.matched) {
return Failure::kNoMatch;
}
auto decl_source = decl_source_range();
const ast::Expression* initializer = nullptr;
if (match(Token::Type::kEqual)) {
auto initializer_expr = expression();
if (initializer_expr.errored) {
return Failure::kErrored;
}
if (!initializer_expr.matched) {
return AddError(peek(), "missing initializer for 'var' declaration");
}
initializer = initializer_expr.value;
}
auto* var = builder_.create<ast::Var>(decl_source, // source
builder_.Ident(decl->name), // symbol
decl->type, // type
decl->address_space, // address space
decl->access, // access control
initializer, // initializer
tint::Empty); // attributes
return create<ast::VariableDeclStatement>(var->source, var);
}
// if_statement
// : attribute* if_clause else_if_clause* else_clause?
// if_clause:
// : IF expression compound_stmt
// else_if_clause:
// : ELSE IF expression compound_stmt
// else_clause
// : ELSE compound_statement
Maybe<const ast::IfStatement*> Parser::if_statement(AttributeList& attrs) {
// Parse if-else chains iteratively instead of recursively, to avoid
// stack-overflow for long chains of if-else statements.
struct IfInfo {
Source source;
const ast::Expression* condition;
const ast::BlockStatement* body;
AttributeList attributes;
};
// Parse an if statement, capturing the source, condition, and body statement.
auto parse_if = [&]() -> Maybe<IfInfo> {
Source source;
if (!match(Token::Type::kIf, &source)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return AddError(peek(), "unable to parse condition expression");
}
auto body = expect_compound_statement("if statement");
if (body.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return IfInfo{source, condition.value, body.value, std::move(attrs)};
};
std::vector<IfInfo> statements;
// Parse the first if statement.
auto first_if = parse_if();
if (first_if.errored) {
return Failure::kErrored;
} else if (!first_if.matched) {
return Failure::kNoMatch;
}
statements.push_back(first_if.value);
// Parse the components of every "else {if}" in the chain.
const ast::Statement* last_stmt = nullptr;
while (continue_parsing()) {
if (!match(Token::Type::kElse)) {
break;
}
// Try to parse an "else if".
auto else_if = parse_if();
if (else_if.errored) {
return Failure::kErrored;
} else if (else_if.matched) {
statements.push_back(else_if.value);
continue;
}
// If it wasn't an "else if", it must just be an "else".
auto else_body = expect_compound_statement("else statement");
if (else_body.errored) {
return Failure::kErrored;
}
last_stmt = else_body.value;
break;
}
// Now walk back through the statements to create their AST nodes.
for (auto itr = statements.rbegin(); itr != statements.rend(); itr++) {
last_stmt = create<ast::IfStatement>(itr->source, itr->condition, itr->body, last_stmt,
std::move(itr->attributes));
}
return last_stmt->As<ast::IfStatement>();
}
// switch_statement
// : attribute* SWITCH expression BRACKET_LEFT switch_body+ BRACKET_RIGHT
Maybe<const ast::SwitchStatement*> Parser::switch_statement(AttributeList& attrs) {
Source source;
if (!match(Token::Type::kSwitch, &source)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return AddError(peek(), "unable to parse selector expression");
}
auto body_attrs = attribute_list();
if (body_attrs.errored) {
return Failure::kErrored;
}
auto body = expect_brace_block("switch statement", [&]() -> Expect<CaseStatementList> {
bool errored = false;
CaseStatementList list;
while (continue_parsing()) {
auto stmt = switch_body();
if (stmt.errored) {
errored = true;
continue;
}
if (!stmt.matched) {
break;
}
list.Push(stmt.value);
}
if (errored) {
return Failure::kErrored;
}
return list;
});
if (body.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::SwitchStatement>(source, condition.value, body.value, std::move(attrs),
std::move(body_attrs.value));
}
// switch_body
// : CASE case_selectors COLON? compound_statement
// | DEFAULT COLON? compound_statement
Maybe<const ast::CaseStatement*> Parser::switch_body() {
if (!peek_is(Token::Type::kCase) && !peek_is(Token::Type::kDefault)) {
return Failure::kNoMatch;
}
auto& t = next();
CaseSelectorList selector_list;
if (t.Is(Token::Type::kCase)) {
auto selectors = expect_case_selectors();
if (selectors.errored) {
return Failure::kErrored;
}
selector_list = std::move(selectors.value);
} else {
// Push the default case selector
selector_list.Push(create<ast::CaseSelector>(t.source()));
}
// Consume the optional colon if present.
match(Token::Type::kColon);
const char* use = "case statement";
auto body = expect_compound_statement(use);
if (body.errored) {
return Failure::kErrored;
}
return create<ast::CaseStatement>(t.source(), selector_list, body.value);
}
// case_selectors
// : case_selector (COMMA case_selector)* COMMA?
Expect<Parser::CaseSelectorList> Parser::expect_case_selectors() {
CaseSelectorList selectors;
while (continue_parsing()) {
auto expr = case_selector();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
break;
}
selectors.Push(expr.value);
if (!match(Token::Type::kComma)) {
break;
}
}
if (selectors.IsEmpty()) {
return AddError(peek(), "expected case selector expression or `default`");
}
return selectors;
}
// case_selector
// : DEFAULT
// | expression
Maybe<const ast::CaseSelector*> Parser::case_selector() {
auto& p = peek();
if (match(Token::Type::kDefault)) {
return create<ast::CaseSelector>(p.source());
}
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return Failure::kNoMatch;
}
return create<ast::CaseSelector>(p.source(), expr.value);
}
// loop_statement
// : attribute* LOOP attribute* BRACKET_LEFT statements continuing_statement? BRACKET_RIGHT
Maybe<const ast::LoopStatement*> Parser::loop_statement(AttributeList& attrs) {
Source source;
if (!match(Token::Type::kLoop, &source)) {
return Failure::kNoMatch;
}
auto body_attrs = attribute_list();
if (body_attrs.errored) {
return Failure::kErrored;
}
Maybe<const ast::BlockStatement*> continuing(Failure::kErrored);
MultiTokenSource body_source(this);
auto body = expect_brace_block("loop", [&]() -> Maybe<StatementList> {
auto stmts = expect_statements();
if (stmts.errored) {
return Failure::kErrored;
}
continuing = continuing_statement();
if (continuing.errored) {
return Failure::kErrored;
}
return stmts;
});
if (body.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::LoopStatement>(
source, create<ast::BlockStatement>(body_source(), body.value, std::move(body_attrs.value)),
continuing.value, std::move(attrs));
}
ForHeader::ForHeader(const ast::Statement* init,
const ast::Expression* cond,
const ast::Statement* cont)
: initializer(init), condition(cond), continuing(cont) {}
ForHeader::~ForHeader() = default;
// (variable_statement | variable_updating_statement | func_call_statement)?
Maybe<const ast::Statement*> Parser::for_header_initializer() {
auto call = func_call_statement();
if (call.errored) {
return Failure::kErrored;
}
if (call.matched) {
return call.value;
}
auto var = variable_statement();
if (var.errored) {
return Failure::kErrored;
}
if (var.matched) {
return var.value;
}
auto assign = variable_updating_statement();
if (assign.errored) {
return Failure::kErrored;
}
if (assign.matched) {
return assign.value;
}
return Failure::kNoMatch;
}
// (variable_updating_statement | func_call_statement)?
Maybe<const ast::Statement*> Parser::for_header_continuing() {
auto call_stmt = func_call_statement();
if (call_stmt.errored) {
return Failure::kErrored;
}
if (call_stmt.matched) {
return call_stmt.value;
}
auto assign = variable_updating_statement();
if (assign.errored) {
return Failure::kErrored;
}
if (assign.matched) {
return assign.value;
}
return Failure::kNoMatch;
}
// for_header
// : for_header_initializer? SEMICOLON expression? SEMICOLON for_header_continuing?
Expect<std::unique_ptr<ForHeader>> Parser::expect_for_header() {
auto initializer = for_header_initializer();
if (initializer.errored) {
return Failure::kErrored;
}
if (!expect("initializer in for loop", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!expect("condition in for loop", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
auto continuing = for_header_continuing();
if (continuing.errored) {
return Failure::kErrored;
}
return std::make_unique<ForHeader>(initializer.value, condition.value, continuing.value);
}
// for_statement
// : FOR PAREN_LEFT for_header PAREN_RIGHT compound_statement
Maybe<const ast::ForLoopStatement*> Parser::for_statement(AttributeList& attrs) {
Source source;
if (!match(Token::Type::kFor, &source)) {
return Failure::kNoMatch;
}
auto header = expect_paren_block("for loop", [&] { return expect_for_header(); });
if (header.errored) {
return Failure::kErrored;
}
auto body = expect_compound_statement("for loop");
if (body.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::ForLoopStatement>(source, header->initializer, header->condition,
header->continuing, body.value, std::move(attrs));
}
// while_statement
// : attribute* WHILE expression compound_statement
Maybe<const ast::WhileStatement*> Parser::while_statement(AttributeList& attrs) {
Source source;
if (!match(Token::Type::kWhile, &source)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return AddError(peek(), "unable to parse while condition expression");
}
auto body = expect_compound_statement("while loop");
if (body.errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::WhileStatement>(source, condition.value, body.value, std::move(attrs));
}
// func_call_statement
// : IDENT argument_expression_list
Maybe<const ast::CallStatement*> Parser::func_call_statement() {
auto& t = peek();
auto& t2 = peek(1);
if (!t.IsIdentifier() || !t2.Is(Token::Type::kParenLeft)) {
return Failure::kNoMatch;
}
next(); // Consume the first peek
auto params = expect_argument_expression_list("function call");
if (params.errored) {
return Failure::kErrored;
}
return builder_.CallStmt(
t.source(),
builder_.Call(t.source(), builder_.Expr(t.source(), t.to_str()), std::move(params.value)));
}
// break_statement
// : BREAK
Maybe<const ast::BreakStatement*> Parser::break_statement() {
Source source;
if (!match(Token::Type::kBreak, &source)) {
return Failure::kNoMatch;
}
return create<ast::BreakStatement>(source);
}
// continue_statement
// : CONTINUE
Maybe<const ast::ContinueStatement*> Parser::continue_statement() {
Source source;
if (!match(Token::Type::kContinue, &source)) {
return Failure::kNoMatch;
}
return create<ast::ContinueStatement>(source);
}
// break_if_statement:
// 'break' 'if' expression semicolon
Maybe<const ast::Statement*> Parser::break_if_statement() {
auto& t1 = peek();
auto& t2 = peek(1);
// Match both the `break` and `if` at the same time.
if (!t1.Is(Token::Type::kBreak) || !t2.Is(Token::Type::kIf)) {
return Failure::kNoMatch;
}
next(); // Consume the peek
next(); // Consume the peek
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(t1, "expected expression for `break-if`");
}
if (!expect("`break-if` statement", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
return create<ast::BreakIfStatement>(t1.source(), expr.value);
}
// continuing_compound_statement:
// attribute* BRACE_LEFT statement* break_if_statement? BRACE_RIGHT
Maybe<const ast::BlockStatement*> Parser::continuing_compound_statement() {
auto attrs = attribute_list();
if (attrs.errored) {
return Failure::kErrored;
}
MultiTokenSource source(this);
auto body = expect_brace_block("", [&]() -> Expect<StatementList> {
StatementList stmts;
while (continue_parsing()) {
// Note, break-if has to parse before statements because statements includes `break`
auto break_if = break_if_statement();
if (break_if.errored) {
return Failure::kErrored;
}
if (break_if.matched) {
stmts.Push(break_if.value);
continue;
}
auto stmt = statement();
if (stmt.errored) {
return Failure::kErrored;
}
if (!stmt.matched) {
break;
}
stmts.Push(stmt.value);
}
return stmts;
});
if (body.errored) {
return Failure::kErrored;
}
return create<ast::BlockStatement>(source(), body.value, std::move(attrs.value));
}
// continuing_statement
// : CONTINUING continuing_compound_statement
Maybe<const ast::BlockStatement*> Parser::continuing_statement() {
if (!match(Token::Type::kContinuing)) {
return create<ast::BlockStatement>(Source{}, tint::Empty, tint::Empty);
}
return continuing_compound_statement();
}
// primary_expression
// : const_literal
// | IDENT argument_expression_list?
// | paren_expression
//
// Note, PAREN_LEFT ( expression ( COMMA expression ) * COMMA? )? PAREN_RIGHT is replaced
// with `argument_expression_list`.
Maybe<const ast::Expression*> Parser::primary_expression() {
auto lit = const_literal();
if (lit.errored) {
return Failure::kErrored;
}
if (lit.matched) {
return lit.value;
}
auto& t = peek();
if (t.IsIdentifier()) {
MultiTokenSource source(this);
next();
const ast::Identifier* ident = nullptr;
if (peek_is(Token::Type::kTemplateArgsLeft)) {
auto tmpl_args = expect_template_arg_block("template arguments", [&] {
return expect_expression_list("template argument list",
Token::Type::kTemplateArgsRight);
});
ident = builder_.Ident(source(), t.to_str(), std::move(tmpl_args.value));
} else {
ident = builder_.Ident(source(), t.to_str());
}
if (peek_is(Token::Type::kParenLeft)) {
auto params = expect_argument_expression_list("function call");
if (params.errored) {
return Failure::kErrored;
}
return builder_.Call(source(), ident, std::move(params.value));
}
return builder_.Expr(ident);
}
if (t.Is(Token::Type::kParenLeft)) {
auto paren = expect_paren_expression();
if (paren.errored) {
return Failure::kErrored;
}
return paren.value;
}
return Failure::kNoMatch;
}
// component_or_swizzle_specifier
// :
// | BRACE_LEFT expression BRACE_RIGHT component_or_swizzle_specifier?
// | PERIOD member_ident component_or_swizzle_specifier?
// | PERIOD swizzle_name component_or_swizzle_specifier?
Maybe<const ast::Expression*> Parser::component_or_swizzle_specifier(
const ast::Expression* prefix) {
MultiTokenSource source(this, prefix->source);
while (continue_parsing()) {
if (match(Token::Type::kBracketLeft)) {
auto res = sync(Token::Type::kBracketRight, [&]() -> Maybe<const ast::Expression*> {
auto param = expression();
if (param.errored) {
return Failure::kErrored;
}
if (!param.matched) {
return AddError(peek(), "unable to parse expression inside []");
}
if (!expect("index accessor", Token::Type::kBracketRight)) {
return Failure::kErrored;
}
return create<ast::IndexAccessorExpression>(source(), prefix, param.value);
});
if (res.errored) {
return res;
}
prefix = res.value;
continue;
}
if (match(Token::Type::kPeriod)) {
auto ident = expect_ident("member accessor");
if (ident.errored) {
return Failure::kErrored;
}
prefix = builder_.MemberAccessor(source(), prefix, ident.value);
continue;
}
return prefix;
}
return Failure::kErrored;
}
// argument_expression_list
// : PAREN_LEFT ((expression COMMA)* expression COMMA?)? PAREN_RIGHT
Expect<Parser::ExpressionList> Parser::expect_argument_expression_list(std::string_view use) {
return expect_paren_block(use, [&]() -> Expect<Parser::ExpressionList> { //
auto list = expression_list(use, Token::Type::kParenRight);
if (list.errored) {
return Failure::kErrored;
}
return list.value;
});
}
// bitwise_expression.post.unary_expression
// : AND unary_expression (AND unary_expression)*
// | OR unary_expression (OR unary_expression)*
// | XOR unary_expression (XOR unary_expression)*
Maybe<const ast::Expression*> Parser::bitwise_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
auto& t = peek();
std::optional<core::BinaryOp> op;
switch (t.type()) {
case Token::Type::kAnd:
op = core::BinaryOp::kAnd;
break;
case Token::Type::kOr:
op = core::BinaryOp::kOr;
break;
case Token::Type::kXor:
op = core::BinaryOp::kXor;
break;
default:
return Failure::kNoMatch;
}
next(); // Consume t
while (continue_parsing()) {
auto rhs = unary_expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
lhs = create<ast::BinaryExpression>(source(), *op, lhs, rhs.value);
if (!match(t.type())) {
return lhs;
}
}
return Failure::kErrored;
}
// multiplicative_operator
// : FORWARD_SLASH
// | MODULO
// | STAR
Maybe<core::BinaryOp> Parser::multiplicative_operator() {
if (match(Token::Type::kForwardSlash)) {
return core::BinaryOp::kDivide;
}
if (match(Token::Type::kMod)) {
return core::BinaryOp::kModulo;
}
if (match(Token::Type::kStar)) {
return core::BinaryOp::kMultiply;
}
return Failure::kNoMatch;
}
// multiplicative_expression.post.unary_expression
// : (multiplicative_operator unary_expression)*
Expect<const ast::Expression*> Parser::expect_multiplicative_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
while (continue_parsing()) {
auto& t = peek();
auto op = multiplicative_operator();
if (op.errored) {
return Failure::kErrored;
}
if (!op.matched) {
return lhs;
}
auto rhs = unary_expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
lhs = create<ast::BinaryExpression>(source(), op.value, lhs, rhs.value);
}
return Failure::kErrored;
}
// additive_operator
// : MINUS
// | PLUS
//
// Note, this also splits a `--` token. This is currently safe as the only way to get into
// here is through additive expression and rules for where `--` are allowed are very restrictive.
Maybe<core::BinaryOp> Parser::additive_operator() {
if (match(Token::Type::kPlus)) {
return core::BinaryOp::kAdd;
}
auto& t = peek();
if (t.Is(Token::Type::kMinusMinus)) {
next();
split_token(Token::Type::kMinus, Token::Type::kMinus);
} else if (t.Is(Token::Type::kMinus)) {
next();
} else {
return Failure::kNoMatch;
}
return core::BinaryOp::kSubtract;
}
// additive_expression.pos.unary_expression
// : (additive_operator unary_expression expect_multiplicative_expression.post.unary_expression)*
//
// This is `( additive_operator unary_expression ( multiplicative_operator unary_expression )* )*`
// split apart.
Expect<const ast::Expression*> Parser::expect_additive_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
while (continue_parsing()) {
auto& t = peek();
auto op = additive_operator();
if (op.errored) {
return Failure::kErrored;
}
if (!op.matched) {
return lhs;
}
auto unary = unary_expression();
if (unary.errored) {
return Failure::kErrored;
}
if (!unary.matched) {
return AddError(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
// The multiplicative binds tighter, so pass the unary into that and build that expression
// before creating the additive expression.
auto rhs = expect_multiplicative_expression_post_unary_expression(unary.value, lhs_source);
if (rhs.errored) {
return Failure::kErrored;
}
lhs = create<ast::BinaryExpression>(source(), op.value, lhs, rhs.value);
}
return Failure::kErrored;
}
// math_expression.post.unary_expression
// : multiplicative_expression.post.unary_expression additive_expression.post.unary_expression
//
// This is `( multiplicative_operator unary_expression )* ( additive_operator unary_expression (
// multiplicative_operator unary_expression )* )*` split apart.
Expect<const ast::Expression*> Parser::expect_math_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
auto rhs = expect_multiplicative_expression_post_unary_expression(lhs, source);
if (rhs.errored) {
return Failure::kErrored;
}
return expect_additive_expression_post_unary_expression(rhs.value, source());
}
// shift_expression
// : unary_expression shift_expression.post.unary_expression
Maybe<const ast::Expression*> Parser::shift_expression() {
MultiTokenSource source(this);
auto lhs = unary_expression();
if (lhs.errored) {
return Failure::kErrored;
}
if (!lhs.matched) {
return Failure::kNoMatch;
}
return expect_shift_expression_post_unary_expression(lhs.value, source);
}
// shift_expression.post.unary_expression
// : math_expression.post.unary_expression?
// | SHIFT_LEFT unary_expression
// | SHIFT_RIGHT unary_expression
//
// Note, add the `math_expression.post.unary_expression` is added here to make
// implementation simpler.
Expect<const ast::Expression*> Parser::expect_shift_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
auto& t = peek();
if (match(Token::Type::kShiftLeft) || match(Token::Type::kShiftRight)) {
std::string name;
std::optional<core::BinaryOp> op;
if (t.Is(Token::Type::kShiftLeft)) {
op = core::BinaryOp::kShiftLeft;
name = "<<";
} else if (t.Is(Token::Type::kShiftRight)) {
op = core::BinaryOp::kShiftRight;
name = ">>";
}
auto& rhs_start = peek();
auto rhs = unary_expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(rhs_start,
std::string("unable to parse right side of ") + name + " expression");
}
return create<ast::BinaryExpression>(source(), *op, lhs, rhs.value);
}
return expect_math_expression_post_unary_expression(lhs, source);
}
// relational_expression
// : unary_expression relational_expression.post.unary_expression
Maybe<const ast::Expression*> Parser::relational_expression() {
MultiTokenSource source(this);
auto lhs = unary_expression();
if (lhs.errored) {
return Failure::kErrored;
}
if (!lhs.matched) {
return Failure::kNoMatch;
}
return expect_relational_expression_post_unary_expression(lhs.value, source);
}
// relational_expression.post.unary_expression
// : shift_expression.post.unary_expression
// | shift_expression.post.unary_expression EQUAL_EQUAL shift_expression
// | shift_expression.post.unary_expression GREATER_THAN shift_expression
// | shift_expression.post.unary_expression GREATER_THAN_EQUAL shift_expression
// | shift_expression.post.unary_expression LESS_THAN shift_expression
// | shift_expression.post.unary_expression LESS_THAN_EQUAL shift_expression
// | shift_expression.post.unary_expression NOT_EQUAL shift_expression
//
// Note, a `shift_expression` element was added to simplify many of the right sides
Expect<const ast::Expression*> Parser::expect_relational_expression_post_unary_expression(
const ast::Expression* lhs,
const Source& lhs_source) {
MultiTokenSource source(this, lhs_source);
auto lhs_result = expect_shift_expression_post_unary_expression(lhs, source);
if (lhs_result.errored) {
return Failure::kErrored;
}
lhs = lhs_result.value;
auto& tok_op = peek();
std::optional<core::BinaryOp> op;
switch (tok_op.type()) {
case Token::Type::kLessThan:
op = core::BinaryOp::kLessThan;
break;
case Token::Type::kGreaterThan:
op = core::BinaryOp::kGreaterThan;
break;
case Token::Type::kLessThanEqual:
op = core::BinaryOp::kLessThanEqual;
break;
case Token::Type::kGreaterThanEqual:
op = core::BinaryOp::kGreaterThanEqual;
break;
case Token::Type::kEqualEqual:
op = core::BinaryOp::kEqual;
break;
case Token::Type::kNotEqual:
op = core::BinaryOp::kNotEqual;
break;
default:
return lhs;
}
next(); // consume tok_op
auto& tok_rhs = peek();
auto rhs = shift_expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(tok_rhs, std::string("unable to parse right side of ") +
std::string(tok_op.to_name()) + " expression");
}
return create<ast::BinaryExpression>(source(), *op, lhs, rhs.value);
}
Expect<const ast::Expression*> Parser::expect_expression(std::string_view use) {
auto& t = peek();
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (expr.matched) {
return expr.value;
}
return AddError(t, "expected expression for " + std::string(use));
}
Maybe<Parser::ExpressionList> Parser::expression_list(std::string_view use,
Token::Type terminator) {
if (peek_is(terminator)) {
return Failure::kNoMatch;
}
auto list = expect_expression_list(use, terminator);
if (list.errored) {
return Failure::kErrored;
}
return list.value;
}
Expect<Parser::ExpressionList> Parser::expect_expression_list(std::string_view use,
Token::Type terminator) {
Parser::ExpressionList exprs;
while (continue_parsing()) {
auto expr = expect_expression(use);
if (expr.errored) {
return Failure::kErrored;
}
exprs.Push(expr.value);
if (peek_is(terminator)) {
break;
}
// Check if the next token is a template start, which was likely intended as a less-than.
if (expect_next_not_template_list(expr->source).errored) {
return Failure::kErrored; // expect_next_not_template_list() raised an error.
}
if (!match(Token::Type::kComma)) {
// Next expression is not a terminator or comma, so this is a parse error.
// Check if last parsed expression was a templated identifier, which was likely indented
// as a less-than / greater-than.
if (expect_not_templated_ident_expr(expr.value).errored) {
return Failure::kErrored; // expect_not_templated_ident_expr() raised an error.
}
// Emit the expected ',' error
expect(use, Token::Type::kComma);
return Failure::kErrored;
}
if (peek_is(terminator)) {
break;
}
}
return exprs;
}
// expression
// : unary_expression bitwise_expression.post.unary_expression
// | unary_expression relational_expression.post.unary_expression
// | unary_expression relational_expression.post.unary_expression and_and
// relational_expression ( and_and relational_expression )*
// | unary_expression relational_expression.post.unary_expression or_or
// relational_expression ( or_or relational_expression )*
//
// Note, a `relational_expression` element was added to simplify many of the right sides
Maybe<const ast::Expression*> Parser::expression() {
MultiTokenSource source(this);
Source first_op;
auto expr = [&]() -> Maybe<const ast::Expression*> {
auto lhs = unary_expression();
if (lhs.errored) {
return Failure::kErrored;
}
if (!lhs.matched) {
return Failure::kNoMatch;
}
first_op = peek().source();
auto bitwise = bitwise_expression_post_unary_expression(lhs.value, source);
if (bitwise.errored) {
return Failure::kErrored;
}
if (bitwise.matched) {
return bitwise.value;
}
auto relational = expect_relational_expression_post_unary_expression(lhs.value, source);
if (relational.errored) {
return Failure::kErrored;
}
auto* ret = relational.value;
auto& t = peek();
if (t.Is(Token::Type::kAndAnd) || t.Is(Token::Type::kOrOr)) {
core::BinaryOp op;
if (t.Is(Token::Type::kAndAnd)) {
op = core::BinaryOp::kLogicalAnd;
} else if (t.Is(Token::Type::kOrOr)) {
op = core::BinaryOp::kLogicalOr;
}
while (continue_parsing()) {
auto& n = peek();
if (!n.Is(t.type())) {
break;
}
next();
auto rhs = relational_expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
ret = create<ast::BinaryExpression>(source(), op, ret, rhs.value);
}
}
return ret;
}();
if (expr.matched) {
// Note, expression is greedy an will consume all the operators of the same type
// so, `a & a & a` would all be consumed above. If you see any binary operator
// after this then it _must_ be a different one, and hence an error.
if (auto* lhs = expr->As<ast::BinaryExpression>()) {
if (auto& n = peek(); n.IsBinaryOperator()) {
AddError(Source::Combine(first_op, n.source()),
std::string("mixing '") + ast::Operator(lhs->op) + "' and '" +
std::string(n.to_name()) + "' requires parenthesis");
return Failure::kErrored;
}
}
}
return expr;
}
// singular_expression
// : primary_expression postfix_expr
Maybe<const ast::Expression*> Parser::singular_expression() {
auto prefix = primary_expression();
if (prefix.errored) {
return Failure::kErrored;
}
if (!prefix.matched) {
return Failure::kNoMatch;
}
return component_or_swizzle_specifier(prefix.value);
}
// unary_expression
// : singular_expression
// | MINUS unary_expression
// | BANG unary_expression
// | TILDE unary_expression
// | STAR unary_expression
// | AND unary_expression
//
// The `primary_expression component_or_swizzle_specifier ?` is moved out into a
// `singular_expression`
Maybe<const ast::Expression*> Parser::unary_expression() {
MultiTokenSource source(this);
auto& t = peek();
if (match(Token::Type::kPlusPlus) || match(Token::Type::kMinusMinus)) {
AddError(source,
"prefix increment and decrement operators are reserved for a "
"future WGSL version");
return Failure::kErrored;
}
core::UnaryOp op;
if (match(Token::Type::kMinus)) {
op = core::UnaryOp::kNegation;
} else if (match(Token::Type::kBang)) {
op = core::UnaryOp::kNot;
} else if (match(Token::Type::kTilde)) {
op = core::UnaryOp::kComplement;
} else if (match(Token::Type::kStar)) {
op = core::UnaryOp::kIndirection;
} else if (match(Token::Type::kAnd)) {
op = core::UnaryOp::kAddressOf;
} else {
return singular_expression();
}
if (parse_depth_ >= kMaxParseDepth) {
// We've hit a maximum parser recursive depth.
// We can't call into unary_expression() as we might stack overflow.
// Instead, report an error
AddError(peek(), "maximum parser recursive depth reached");
return Failure::kErrored;
}
++parse_depth_;
auto expr = unary_expression();
--parse_depth_;
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(
peek(), "unable to parse right side of " + std::string(t.to_name()) + " expression");
}
return create<ast::UnaryOpExpression>(source(), op, expr.value);
}
// compound_assignment_operator
// : plus_equal
// | minus_equal
// | times_equal
// | division_equal
// | modulo_equal
// | and_equal
// | or_equal
// | xor_equal
// | shift_right_equal
// | shift_left_equal
Maybe<core::BinaryOp> Parser::compound_assignment_operator() {
std::optional<core::BinaryOp> compound_op;
if (peek_is(Token::Type::kPlusEqual)) {
compound_op = core::BinaryOp::kAdd;
} else if (peek_is(Token::Type::kMinusEqual)) {
compound_op = core::BinaryOp::kSubtract;
} else if (peek_is(Token::Type::kTimesEqual)) {
compound_op = core::BinaryOp::kMultiply;
} else if (peek_is(Token::Type::kDivisionEqual)) {
compound_op = core::BinaryOp::kDivide;
} else if (peek_is(Token::Type::kModuloEqual)) {
compound_op = core::BinaryOp::kModulo;
} else if (peek_is(Token::Type::kAndEqual)) {
compound_op = core::BinaryOp::kAnd;
} else if (peek_is(Token::Type::kOrEqual)) {
compound_op = core::BinaryOp::kOr;
} else if (peek_is(Token::Type::kXorEqual)) {
compound_op = core::BinaryOp::kXor;
} else if (peek_is(Token::Type::kShiftLeftEqual)) {
compound_op = core::BinaryOp::kShiftLeft;
} else if (peek_is(Token::Type::kShiftRightEqual)) {
compound_op = core::BinaryOp::kShiftRight;
}
if (compound_op) {
next();
return *compound_op;
}
return Failure::kNoMatch;
}
// core_lhs_expression
// : ident
// | PAREN_LEFT lhs_expression PAREN_RIGHT
Maybe<const ast::Expression*> Parser::core_lhs_expression() {
auto& t = peek();
if (t.IsIdentifier()) {
next();
return builder_.Expr(t.source(), t.to_str());
}
if (peek_is(Token::Type::kParenLeft)) {
return expect_paren_block("", [&]() -> Expect<const ast::Expression*> {
auto expr = lhs_expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(t, "invalid expression");
}
return expr.value;
});
}
return Failure::kNoMatch;
}
// lhs_expression
// : core_lhs_expression component_or_swizzle_specifier ?
// | AND lhs_expression
// | STAR lhs_expression
Maybe<const ast::Expression*> Parser::lhs_expression() {
auto core_expr = core_lhs_expression();
if (core_expr.errored) {
return Failure::kErrored;
}
if (core_expr.matched) {
return component_or_swizzle_specifier(core_expr.value);
}
// Gather up all the `*`, `&` and `&&` tokens into a list and create all of the unary ops at
// once instead of recursing. This handles the case where the fuzzer decides >8k `*`s would be
// fun.
struct LHSData {
Source source;
core::UnaryOp op;
};
Vector<LHSData, 4> ops;
while (true) {
auto& t = peek();
if (!t.Is(Token::Type::kAndAnd) && !t.Is(Token::Type::kAnd) && !t.Is(Token::Type::kStar)) {
break;
}
next(); // consume the peek
if (t.Is(Token::Type::kAndAnd)) {
// The first `&` is consumed as part of the `&&`, so we only push one of the two `&`s.
split_token(Token::Type::kAnd, Token::Type::kAnd);
ops.Push({t.source(), core::UnaryOp::kAddressOf});
} else if (t.Is(Token::Type::kAnd)) {
ops.Push({t.source(), core::UnaryOp::kAddressOf});
} else if (t.Is(Token::Type::kStar)) {
ops.Push({t.source(), core::UnaryOp::kIndirection});
}
}
if (ops.IsEmpty()) {
return Failure::kNoMatch;
}
auto& t = peek();
auto expr = lhs_expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return AddError(t, "missing expression");
}
const ast::Expression* ret = expr.value;
// Consume the ops in reverse order so we have the correct AST ordering.
for (auto& info : tint::Reverse(ops)) {
ret = create<ast::UnaryOpExpression>(info.source, info.op, ret);
}
return ret;
}
// variable_updating_statement
// : lhs_expression ( EQUAL | compound_assignment_operator ) expression
// | lhs_expression MINUS_MINUS
// | lhs_expression PLUS_PLUS
// | UNDERSCORE EQUAL expression
//
// Note, this is a simplification of the recursive grammar statement with the `lhs_expression`
// substituted back into the expression.
Maybe<const ast::Statement*> Parser::variable_updating_statement() {
auto& t = peek();
// tint:295 - Test for `ident COLON` - this is invalid grammar, and without
// special casing will error as "missing = for assignment", which is less
// helpful than this error message:
if (peek_is(Token::Type::kIdentifier) && peek_is(Token::Type::kColon, 1)) {
return AddError(peek(0).source(), "expected 'var' for variable declaration");
}
Source source;
const ast::Expression* lhs = nullptr;
std::optional<core::BinaryOp> compound_op;
if (peek_is(Token::Type::kUnderscore)) {
next(); // Consume the peek.
if (!expect("assignment", Token::Type::kEqual)) {
return Failure::kErrored;
}
source = last_source();
lhs = create<ast::PhonyExpression>(t.source());
} else {
auto lhs_result = lhs_expression();
if (lhs_result.errored) {
return Failure::kErrored;
}
if (!lhs_result.matched) {
return Failure::kNoMatch;
}
lhs = lhs_result.value;
// Handle increment and decrement statements.
if (match(Token::Type::kPlusPlus)) {
return create<ast::IncrementDecrementStatement>(last_source(), lhs, true);
}
if (match(Token::Type::kMinusMinus)) {
return create<ast::IncrementDecrementStatement>(last_source(), lhs, false);
}
source = peek().source();
auto compound_op_result = compound_assignment_operator();
if (compound_op_result.errored) {
return Failure::kErrored;
}
if (compound_op_result.matched) {
compound_op = compound_op_result.value;
} else {
if (!expect("assignment", Token::Type::kEqual)) {
return Failure::kErrored;
}
}
}
auto rhs = expression();
if (rhs.errored) {
return Failure::kErrored;
}
if (!rhs.matched) {
return AddError(peek(), "unable to parse right side of assignment");
}
if (compound_op) {
return create<ast::CompoundAssignmentStatement>(source, lhs, rhs.value, *compound_op);
}
return create<ast::AssignmentStatement>(source, lhs, rhs.value);
}
// const_literal
// : INT_LITERAL
// | FLOAT_LITERAL
// | bool_literal
//
// bool_literal
// : TRUE
// | FALSE
Maybe<const ast::LiteralExpression*> Parser::const_literal() {
auto& t = peek();
if (match(Token::Type::kIntLiteral)) {
return create<ast::IntLiteralExpression>(t.source(), t.to_i64(),
ast::IntLiteralExpression::Suffix::kNone);
}
if (match(Token::Type::kIntLiteral_I)) {
return create<ast::IntLiteralExpression>(t.source(), t.to_i64(),
ast::IntLiteralExpression::Suffix::kI);
}
if (match(Token::Type::kIntLiteral_U)) {
return create<ast::IntLiteralExpression>(t.source(), t.to_i64(),
ast::IntLiteralExpression::Suffix::kU);
}
if (match(Token::Type::kFloatLiteral)) {
return create<ast::FloatLiteralExpression>(t.source(), t.to_f64(),
ast::FloatLiteralExpression::Suffix::kNone);
}
if (match(Token::Type::kFloatLiteral_F)) {
return create<ast::FloatLiteralExpression>(t.source(), t.to_f64(),
ast::FloatLiteralExpression::Suffix::kF);
}
if (match(Token::Type::kFloatLiteral_H)) {
return create<ast::FloatLiteralExpression>(t.source(), t.to_f64(),
ast::FloatLiteralExpression::Suffix::kH);
}
if (match(Token::Type::kTrue)) {
return create<ast::BoolLiteralExpression>(t.source(), true);
}
if (match(Token::Type::kFalse)) {
return create<ast::BoolLiteralExpression>(t.source(), false);
}
if (handle_error(t)) {
return Failure::kErrored;
}
return Failure::kNoMatch;
}
Maybe<Parser::AttributeList> Parser::attribute_list() {
bool errored = false;
AttributeList attrs;
while (continue_parsing()) {
if (match(Token::Type::kAttr)) {
if (auto attr = expect_attribute(); attr.errored) {
errored = true;
} else {
attrs.Push(attr.value);
}
} else {
break;
}
}
if (errored) {
return Failure::kErrored;
}
if (attrs.IsEmpty()) {
return Failure::kNoMatch;
}
return attrs;
}
Expect<const ast::Attribute*> Parser::expect_attribute() {
auto& t = peek();
auto attr = attribute();
if (attr.errored) {
return Failure::kErrored;
}
if (attr.matched) {
return attr.value;
}
return AddError(t, "expected attribute");
}
// attribute
// : ATTR identifier ( PAREN_LEFT expression ( COMMA expression )? COMMA? PAREN_RIGHT )?
Maybe<const ast::Attribute*> Parser::attribute() {
// Note, the ATTR is matched by the called `attribute_list` in this case, so it is not matched
// here and this has to be an attribute.
auto& t = peek();
if (match(Token::Type::kConst)) {
return AddError(t.source(), "const attribute may not appear in shaders");
}
if (match(Token::Type::kDiagnostic)) {
auto control = expect_diagnostic_control();
if (control.errored) {
return Failure::kErrored;
}
return create<ast::DiagnosticAttribute>(t.source(), std::move(control.value));
}
auto attr = expect_enum("attribute", core::ParseAttribute, core::kAttributeStrings);
if (attr.errored) {
return Failure::kErrored;
}
uint32_t min = 1;
uint32_t max = 1;
switch (attr.value) {
case core::Attribute::kCompute:
case core::Attribute::kFragment:
case core::Attribute::kInvariant:
case core::Attribute::kMustUse:
case core::Attribute::kVertex:
min = 0;
max = 0;
break;
case core::Attribute::kInterpolate:
max = 2;
break;
case core::Attribute::kWorkgroupSize:
max = 3;
break;
default:
break;
}
Vector<const ast::Expression*, 2> args;
// Handle no parameter items which should have no parens
if (min == 0) {
auto& t2 = peek();
if (match(Token::Type::kParenLeft)) {
return AddError(t2.source(), t.to_str() + " attribute doesn't take parenthesis");
}
} else {
auto res = expect_paren_block(t.to_str() + " attribute", [&]() -> Expect<bool> {
while (continue_parsing()) {
if (peek().Is(Token::Type::kParenRight)) {
break;
}
auto expr = expect_expression(t.to_str());
if (expr.errored) {
return Failure::kErrored;
}
args.Push(expr.value);
if (!match(Token::Type::kComma)) {
break;
}
}
return true;
});
if (res.errored) {
return Failure::kErrored;
}
if (args.IsEmpty() || args.Length() < min) {
return AddError(t.source(),
t.to_str() + " expects" + (min != max ? " at least " : " ") +
std::to_string(min) + " argument" + (min != 1 ? "s" : ""));
}
if (args.Length() > max) {
return AddError(t.source(), t.to_str() + " expects" + (min != max ? " at most " : " ") +
std::to_string(max) + " argument" +
(max != 1 ? "s" : "") + ", got " +
std::to_string(args.Length()));
}
}
switch (attr.value) {
case core::Attribute::kAlign:
return create<ast::StructMemberAlignAttribute>(t.source(), args[0]);
case core::Attribute::kBinding:
return create<ast::BindingAttribute>(t.source(), args[0]);
case core::Attribute::kBlendSrc:
return create<ast::BlendSrcAttribute>(t.source(), args[0]);
case core::Attribute::kBuiltin:
return create<ast::BuiltinAttribute>(t.source(), args[0]);
case core::Attribute::kColor:
return create<ast::ColorAttribute>(t.source(), args[0]);
case core::Attribute::kCompute:
return create<ast::StageAttribute>(t.source(), ast::PipelineStage::kCompute);
case core::Attribute::kFragment:
return create<ast::StageAttribute>(t.source(), ast::PipelineStage::kFragment);
case core::Attribute::kGroup:
return create<ast::GroupAttribute>(t.source(), args[0]);
case core::Attribute::kId:
return create<ast::IdAttribute>(t.source(), args[0]);
case core::Attribute::kInputAttachmentIndex:
return create<ast::InputAttachmentIndexAttribute>(t.source(), args[0]);
case core::Attribute::kInterpolate:
return create<ast::InterpolateAttribute>(t.source(), args[0],
args.Length() == 2 ? args[1] : nullptr);
case core::Attribute::kInvariant:
return create<ast::InvariantAttribute>(t.source());
case core::Attribute::kLocation:
return builder_.Location(t.source(), args[0]);
case core::Attribute::kMustUse:
return create<ast::MustUseAttribute>(t.source());
case core::Attribute::kSize:
return builder_.MemberSize(t.source(), args[0]);
case core::Attribute::kVertex:
return create<ast::StageAttribute>(t.source(), ast::PipelineStage::kVertex);
case core::Attribute::kWorkgroupSize:
return create<ast::WorkgroupAttribute>(t.source(), args[0],
args.Length() > 1 ? args[1] : nullptr,
args.Length() > 2 ? args[2] : nullptr);
default:
return Failure::kNoMatch;
}
}
Expect<Void> Parser::expect_attributes_consumed(VectorRef<const ast::Attribute*> in) {
if (in.IsEmpty()) {
return kSuccess;
}
AddError(in[0]->source, "unexpected attributes");
return Failure::kErrored;
}
Expect<Void> Parser::expect_next_not_template_list(const Source& lhs_source) {
Source end;
if (!match(Token::Type::kTemplateArgsLeft, &end)) {
return kSuccess;
}
// Try to find end of template
for (size_t i = 0; i < 32; i++) {
if (auto& t = peek(i); t.type() == Token::Type::kTemplateArgsRight) {
end = t.source();
}
}
Source template_source = lhs_source;
template_source.range.end = end.range.end;
AddError(template_source, "parsed as template list");
if (auto rhs = expression(); rhs.matched) {
Source lt_source = lhs_source;
lt_source.range.end = rhs->source.range.end;
AddNote(lt_source,
"if this is intended to be a less-than expression then wrap in parentheses");
}
return Failure::kErrored;
}
Expect<Void> Parser::expect_not_templated_ident_expr(const ast::Expression* expr) {
auto* ident_expr = expr->As<ast::IdentifierExpression>();
if (!ident_expr) {
return kSuccess;
}
auto* ident = ident_expr->identifier->As<ast::TemplatedIdentifier>();
if (!ident) {
return kSuccess;
}
AddError(ident->source, "parsed as template list");
if (auto rhs = expression(); rhs.matched) {
Source gt_source = ident->arguments.Back()->source;
gt_source.range.end = rhs->source.range.end;
AddNote(gt_source,
"if this is intended to be a greater-than expression then wrap in parentheses");
}
return Failure::kErrored;
}
// severity_control_name
// : 'error'
// | 'warning'
// | 'info'
// | 'off'
Expect<wgsl::DiagnosticSeverity> Parser::expect_severity_control_name() {
return expect_enum("severity control", wgsl::ParseDiagnosticSeverity,
wgsl::kDiagnosticSeverityStrings);
}
// diagnostic_control
// : PAREN_LEFT severity_control_name COMMA diagnostic_rule_name COMMA ? PAREN_RIGHT
Expect<ast::DiagnosticControl> Parser::expect_diagnostic_control() {
return expect_paren_block("diagnostic control", [&]() -> Expect<ast::DiagnosticControl> {
auto severity_control = expect_severity_control_name();
if (severity_control.errored) {
return Failure::kErrored;
}
if (!expect("diagnostic control", Token::Type::kComma)) {
return Failure::kErrored;
}
auto rule_name = expect_diagnostic_rule_name();
if (rule_name.errored) {
return Failure::kErrored;
}
match(Token::Type::kComma);
return ast::DiagnosticControl(severity_control.value, rule_name.value);
});
}
// diagnostic_rule_name :
// | diagnostic_name_token
// | diagnostic_name_token '.' diagnostic_name_token
Expect<const ast::DiagnosticRuleName*> Parser::expect_diagnostic_rule_name() {
if (peek_is(Token::Type::kPeriod, 1)) {
auto category = expect_ident("", "diagnostic rule category");
if (category.errored) {
return Failure::kErrored;
}
if (!expect("diagnostic rule", Token::Type::kPeriod)) {
return Failure::kErrored;
}
auto name = expect_ident("", "diagnostic rule name");
if (name.errored) {
return Failure::kErrored;
}
return builder_.DiagnosticRuleName(category.value, name.value);
}
auto name = expect_ident("", "diagnostic rule name");
if (name.errored) {
return Failure::kErrored;
}
return builder_.DiagnosticRuleName(name.value);
}
bool Parser::match(Token::Type tok, Source* source /*= nullptr*/) {
auto& t = peek();
if (source != nullptr) {
*source = t.source();
}
if (t.Is(tok)) {
next();
return true;
}
return false;
}
bool Parser::expect(std::string_view use, Token::Type tok) {
auto& t = peek();
if (t.Is(tok)) {
next();
synchronized_ = true;
return true;
}
// Special case to split `>>` and `>=` tokens if we are looking for a `>`.
if (tok == Token::Type::kGreaterThan &&
(t.Is(Token::Type::kShiftRight) || t.Is(Token::Type::kGreaterThanEqual))) {
next();
// Push the second character to the token queue.
if (t.Is(Token::Type::kShiftRight)) {
split_token(Token::Type::kGreaterThan, Token::Type::kGreaterThan);
} else if (t.Is(Token::Type::kGreaterThanEqual)) {
split_token(Token::Type::kGreaterThan, Token::Type::kEqual);
}
synchronized_ = true;
return true;
}
// Error cases
synchronized_ = false;
if (handle_error(t)) {
return false;
}
StringStream err;
if (tok == Token::Type::kTemplateArgsLeft && t.type() == Token::Type::kLessThan) {
err << "missing closing '>'";
} else {
err << "expected '" << Token::TypeToName(tok) << "'";
}
if (!use.empty()) {
err << " for " << use;
}
AddError(t, err.str());
return false;
}
Expect<int32_t> Parser::expect_sint(std::string_view use, Source* source /* = nullptr */) {
auto& t = peek();
if (source) {
*source = t.source();
}
if (!t.Is(Token::Type::kIntLiteral) && !t.Is(Token::Type::kIntLiteral_I)) {
return AddError(t.source(), "expected signed integer literal", use);
}
int64_t val = t.to_i64();
if ((val > std::numeric_limits<int32_t>::max()) ||
(val < std::numeric_limits<int32_t>::min())) {
// TODO(crbug.com/tint/1504): Test this when abstract int is implemented
return AddError(t.source(), "value overflows i32", use);
}
next();
return static_cast<int32_t>(t.to_i64());
}
Expect<uint32_t> Parser::expect_positive_sint(std::string_view use) {
Source source;
auto sint = expect_sint(use, &source);
if (sint.errored) {
return Failure::kErrored;
}
if (sint.value < 0) {
return AddError(source, std::string(use) + " must be positive");
}
return static_cast<uint32_t>(sint.value);
}
Expect<uint32_t> Parser::expect_nonzero_positive_sint(std::string_view use) {
Source source;
auto sint = expect_sint(use, &source);
if (sint.errored) {
return Failure::kErrored;
}
if (sint.value <= 0) {
return AddError(source, std::string(use) + " must be greater than 0");
}
return static_cast<uint32_t>(sint.value);
}
Expect<const ast::Identifier*> Parser::expect_ident(std::string_view use,
std::string_view kind /* = "identifier" */) {
auto& t = peek();
if (t.IsIdentifier()) {
synchronized_ = true;
next();
if (is_reserved(t)) {
return AddError(t.source(), "'" + t.to_str() + "' is a reserved keyword");
}
return builder_.Ident(t.source(), t.to_str());
}
if (handle_error(t)) {
return Failure::kErrored;
}
synchronized_ = false;
return AddError(t.source(), "expected " + std::string(kind), use);
}
template <typename F, typename T>
T Parser::expect_block(Token::Type start, Token::Type end, std::string_view use, F&& body) {
if (!expect(use, start)) {
return Failure::kErrored;
}
return sync(end, [&]() -> T {
auto res = body();
if (res.errored) {
return Failure::kErrored;
}
if (!expect(use, end)) {
return Failure::kErrored;
}
return res;
});
}
template <typename F, typename T>
T Parser::expect_paren_block(std::string_view use, F&& body) {
return expect_block(Token::Type::kParenLeft, Token::Type::kParenRight, use,
std::forward<F>(body));
}
template <typename F, typename T>
T Parser::expect_brace_block(std::string_view use, F&& body) {
return expect_block(Token::Type::kBraceLeft, Token::Type::kBraceRight, use,
std::forward<F>(body));
}
template <typename F, typename T>
T Parser::expect_lt_gt_block(std::string_view use, F&& body) {
return expect_block(Token::Type::kLessThan, Token::Type::kGreaterThan, use,
std::forward<F>(body));
}
template <typename F, typename T>
T Parser::expect_template_arg_block(std::string_view use, F&& body) {
return expect_block(Token::Type::kTemplateArgsLeft, Token::Type::kTemplateArgsRight, use,
std::forward<F>(body));
}
template <typename F, typename T>
T Parser::sync(Token::Type tok, F&& body) {
if (parse_depth_ >= kMaxParseDepth) {
// We've hit a maximum parser recursive depth.
// We can't call into body() as we might stack overflow.
// Instead, report an error...
AddError(peek(), "maximum parser recursive depth reached");
// ...and try to resynchronize. If we cannot resynchronize to `tok` then
// synchronized_ is set to false, and the parser knows that forward progress
// is not being made.
sync_to(tok, /* consume: */ true);
return Failure::kErrored;
}
sync_tokens_.push_back(tok);
++parse_depth_;
auto result = body();
--parse_depth_;
if (TINT_UNLIKELY(sync_tokens_.back() != tok)) {
TINT_ICE() << "sync_tokens is out of sync";
}
sync_tokens_.pop_back();
if (result.errored) {
sync_to(tok, /* consume: */ true);
}
return result;
}
bool Parser::sync_to(Token::Type tok, bool consume) {
// Clear the synchronized state - gets set to true again on success.
synchronized_ = false;
BlockCounters counters;
for (size_t i = 0; i < kMaxResynchronizeLookahead; i++) {
auto& t = peek(i);
if (counters.consume(t) > 0) {
continue; // Nested block
}
if (!t.Is(tok) && !is_sync_token(t)) {
continue; // Not a synchronization point
}
// Synchronization point found.
// Skip any tokens we don't understand, bringing us to just before the
// resync point.
while (i-- > 0) {
next();
}
// Is this synchronization token |tok|?
if (t.Is(tok)) {
if (consume) {
next();
}
synchronized_ = true;
return true;
}
break;
}
return false;
}
bool Parser::is_sync_token(const Token& t) const {
for (auto r : sync_tokens_) {
if (t.Is(r)) {
return true;
}
}
return false;
}
bool Parser::handle_error(const Token& t) {
// The token might itself be an error.
if (t.IsError()) {
synchronized_ = false;
AddError(t.source(), t.to_str());
return true;
}
return false;
}
template <typename F, typename T>
T Parser::without_diag(F&& body) {
silence_diags_++;
auto result = body();
silence_diags_--;
return result;
}
} // namespace tint::wgsl::reader