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// Copyright 2020 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "src/tint/reader/wgsl/parser_impl.h"
#include <limits>
#include "src/tint/ast/array.h"
#include "src/tint/ast/assignment_statement.h"
#include "src/tint/ast/bitcast_expression.h"
#include "src/tint/ast/break_if_statement.h"
#include "src/tint/ast/break_statement.h"
#include "src/tint/ast/call_statement.h"
#include "src/tint/ast/continue_statement.h"
#include "src/tint/ast/discard_statement.h"
#include "src/tint/ast/external_texture.h"
#include "src/tint/ast/id_attribute.h"
#include "src/tint/ast/if_statement.h"
#include "src/tint/ast/increment_decrement_statement.h"
#include "src/tint/ast/invariant_attribute.h"
#include "src/tint/ast/loop_statement.h"
#include "src/tint/ast/return_statement.h"
#include "src/tint/ast/stage_attribute.h"
#include "src/tint/ast/switch_statement.h"
#include "src/tint/ast/type_name.h"
#include "src/tint/ast/unary_op_expression.h"
#include "src/tint/ast/variable_decl_statement.h"
#include "src/tint/ast/vector.h"
#include "src/tint/ast/workgroup_attribute.h"
#include "src/tint/reader/wgsl/lexer.h"
#include "src/tint/sem/depth_texture.h"
#include "src/tint/sem/external_texture.h"
#include "src/tint/sem/multisampled_texture.h"
#include "src/tint/sem/sampled_texture.h"
#include "src/tint/utils/reverse.h"
#include "src/tint/utils/string.h"
namespace tint::reader::wgsl {
namespace {
using Void = ParserImpl::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 = ParserImpl::Expect<T>;
template <typename T>
using Maybe = ParserImpl::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
bool is_reserved(const Token& t) {
return t == "CompileShader" || t == "ComputeShader" || t == "DomainShader" ||
t == "GeometryShader" || t == "Hullshader" || t == "NULL" || t == "Self" ||
t == "abstract" || t == "active" || t == "alignas" || t == "alignof" || t == "as" ||
t == "asm" || t == "asm_fragment" || t == "async" || t == "attribute" || t == "auto" ||
t == "await" || t == "become" || t == "binding_array" || t == "cast" || t == "catch" ||
t == "class" || t == "co_await" || t == "co_return" || t == "co_yield" ||
t == "coherent" || t == "column_major" || t == "common" || t == "compile" ||
t == "compile_fragment" || t == "concept" || t == "const_cast" || t == "consteval" ||
t == "constexpr" || t == "constinit" || t == "crate" || t == "debugger" ||
t == "decltype" || t == "delete" || t == "demote" || t == "demote_to_helper" ||
t == "do" || t == "dynamic_cast" || t == "enum" || t == "explicit" || t == "export" ||
t == "extends" || t == "extern" || t == "external" || t == "filter" || t == "final" ||
t == "finally" || t == "friend" || t == "from" || t == "fxgroup" || t == "get" ||
t == "goto" || t == "groupshared" || t == "handle" || t == "highp" || t == "impl" ||
t == "implements" || t == "import" || t == "inline" || t == "inout" ||
t == "instanceof" || t == "interface" || t == "invariant" || t == "layout" ||
t == "lowp" || t == "macro" || t == "macro_rules" || t == "match" || t == "mediump" ||
t == "meta" || t == "mod" || t == "module" || t == "move" || t == "mut" ||
t == "mutable" || t == "namespace" || t == "new" || t == "nil" || t == "noexcept" ||
t == "noinline" || t == "nointerpolation" || t == "noperspective" || t == "null" ||
t == "nullptr" || t == "of" || t == "operator" || t == "package" || t == "packoffset" ||
t == "partition" || t == "pass" || t == "patch" || t == "pixelfragment" ||
t == "precise" || t == "precision" || t == "premerge" || t == "priv" ||
t == "protected" || t == "pub" || t == "public" || t == "readonly" || t == "ref" ||
t == "regardless" || t == "register" || t == "reinterpret_cast" || t == "requires" ||
t == "resource" || t == "restrict" || t == "self" || t == "set" || t == "shared" ||
t == "signed" || t == "sizeof" || t == "smooth" || t == "snorm" || t == "static" ||
t == "static_cast" || t == "std" || t == "subroutine" || t == "super" || t == "target" ||
t == "template" || t == "this" || t == "thread_local" || t == "throw" || t == "trait" ||
t == "try" || t == "typedef" || t == "typeid" || t == "typename" || t == "typeof" ||
t == "union" || t == "unless" || t == "unorm" || t == "unsafe" || t == "unsized" ||
t == "use" || t == "using" || t == "varying" || t == "virtual" || t == "volatile" ||
t == "wgsl" || t == "where" || t == "with" || t == "writeonly" || t == "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 ParserImpl::MultiTokenSource {
public:
/// Constructor that starts with Source at the current peek position
/// @param parser the parser
explicit MultiTokenSource(ParserImpl* 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(ParserImpl* 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 Source() const {
auto end = parser_->last_source().End();
if (end < start_) {
end = start_;
}
return Source::Combine(start_, end);
}
/// Implicit conversion to Source that returns the combined source from start to the current
/// last token's source.
operator tint::Source() const { return Source(); }
private:
ParserImpl* parser_;
tint::Source start_;
};
ParserImpl::TypedIdentifier::TypedIdentifier() = default;
ParserImpl::TypedIdentifier::TypedIdentifier(const TypedIdentifier&) = default;
ParserImpl::TypedIdentifier::TypedIdentifier(const ast::Type* type_in,
std::string name_in,
Source source_in)
: type(type_in), name(std::move(name_in)), source(std::move(source_in)) {}
ParserImpl::TypedIdentifier::~TypedIdentifier() = default;
ParserImpl::FunctionHeader::FunctionHeader() = default;
ParserImpl::FunctionHeader::FunctionHeader(const FunctionHeader&) = default;
ParserImpl::FunctionHeader::FunctionHeader(Source src,
std::string n,
utils::VectorRef<const ast::Parameter*> p,
const ast::Type* ret_ty,
utils::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)) {}
ParserImpl::FunctionHeader::~FunctionHeader() = default;
ParserImpl::FunctionHeader& ParserImpl::FunctionHeader::operator=(const FunctionHeader& rhs) =
default;
ParserImpl::VarDeclInfo::VarDeclInfo() = default;
ParserImpl::VarDeclInfo::VarDeclInfo(const VarDeclInfo&) = default;
ParserImpl::VarDeclInfo::VarDeclInfo(Source source_in,
std::string name_in,
ast::AddressSpace address_space_in,
ast::Access access_in,
const ast::Type* type_in)
: source(std::move(source_in)),
name(std::move(name_in)),
address_space(address_space_in),
access(access_in),
type(type_in) {}
ParserImpl::VarDeclInfo::~VarDeclInfo() = default;
ParserImpl::ParserImpl(Source::File const* file) : file_(file) {}
ParserImpl::~ParserImpl() = default;
ParserImpl::Failure::Errored ParserImpl::add_error(const Source& source,
std::string_view err,
std::string_view use) {
std::stringstream msg;
msg << err;
if (!use.empty()) {
msg << " for " << use;
}
add_error(source, msg.str());
return Failure::kErrored;
}
ParserImpl::Failure::Errored ParserImpl::add_error(const Token& t, const std::string& err) {
add_error(t.source(), err);
return Failure::kErrored;
}
ParserImpl::Failure::Errored ParserImpl::add_error(const Source& source, const std::string& err) {
if (silence_errors_ == 0) {
builder_.Diagnostics().add_error(diag::System::Reader, err, source);
}
return Failure::kErrored;
}
void ParserImpl::deprecated(const Source& source, const std::string& msg) {
builder_.Diagnostics().add_warning(diag::System::Reader,
"use of deprecated language feature: " + msg, source);
}
const Token& ParserImpl::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& ParserImpl::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 ParserImpl::peek_is(Token::Type tok, size_t idx) {
return peek(idx).Is(tok);
}
void ParserImpl::split_token(Token::Type lhs, Token::Type rhs) {
if (next_token_idx_ == 0) {
TINT_ICE(Reader, builder_.Diagnostics())
<< "attempt to update placeholder at beginning of tokens";
}
if (next_token_idx_ >= tokens_.size()) {
TINT_ICE(Reader, builder_.Diagnostics())
<< "attempt to update placeholder past end of tokens";
}
if (!tokens_[next_token_idx_].IsPlaceholder()) {
TINT_ICE(Reader, builder_.Diagnostics()) << "attempt to update non-placeholder token";
}
tokens_[next_token_idx_ - 1].SetType(lhs);
tokens_[next_token_idx_].SetType(rhs);
}
Source ParserImpl::last_source() const {
return tokens_[last_source_idx_].source();
}
void ParserImpl::InitializeLex() {
Lexer l{file_};
tokens_ = l.Lex();
}
bool ParserImpl::Parse() {
InitializeLex();
translation_unit();
return !has_error();
}
// translation_unit
// : global_directive* global_decl* EOF
void ParserImpl::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) {
add_error(p, "unexpected token");
}
}
if (builder_.Diagnostics().error_count() >= max_errors_) {
add_error(Source{{}, p.source().file},
"stopping after " + std::to_string(max_errors_) + " errors");
break;
}
}
}
// global_directive
// : enable_directive
Maybe<Void> ParserImpl::global_directive(bool have_parsed_decl) {
auto& p = peek();
auto ed = enable_directive();
if (ed.matched && have_parsed_decl) {
return add_error(p, "enable directives must come before all global declarations");
}
return ed;
}
// enable_directive
// : enable name SEMICLON
Maybe<Void> ParserImpl::enable_directive() {
auto decl = sync(Token::Type::kSemicolon, [&]() -> Maybe<Void> {
if (!match(Token::Type::kEnable)) {
return Failure::kNoMatch;
}
// Match the extension 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 `enable(foo);` instead of `enable foo;`.
synchronized_ = false;
return add_error(t.source(), "enable directives don't take parenthesis");
}
auto extension = ast::Extension::kUndefined;
if (t.Is(Token::Type::kF16)) {
// `f16` is a valid extension name and also a keyword
synchronized_ = true;
next();
extension = ast::Extension::kF16;
} else {
auto ext = expect_enum("extension", ast::ParseExtension, ast::kExtensionStrings);
if (ext.errored) {
return Failure::kErrored;
}
extension = ext.value;
}
if (!expect("enable directive", Token::Type::kSemicolon)) {
return Failure::kErrored;
}
builder_.AST().AddEnable(create<ast::Enable>(t.source(), extension));
return kSuccess;
});
if (decl.errored) {
return Failure::kErrored;
}
if (decl.matched) {
return kSuccess;
}
return Failure::kNoMatch;
}
// global_decl
// : SEMICOLON
// | global_variable_decl SEMICOLON
// | global_constant_decl SEMICOLON
// | type_alias_decl SEMICOLON
// | struct_decl
// | function_decl
// | static_assert_statement SEMICOLON
Maybe<Void> ParserImpl::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;
}
}
builder_.AST().AddGlobalVariable(gc.value);
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 = static_assert_statement();
if (assertion.errored) {
return Failure::kErrored;
}
if (assertion.matched) {
builder_.AST().AddStaticAssert(assertion.value);
if (!expect("static 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)) {
return Failure::kErrored;
}
return kSuccess;
}
auto str = struct_decl();
if (str.errored) {
errored = true;
}
if (str.matched) {
builder_.AST().AddTypeDecl(str.value);
if (!expect_attributes_consumed(attrs.value)) {
return Failure::kErrored;
}
return kSuccess;
}
auto func = function_decl(attrs.value);
if (func.errored) {
errored = true;
}
if (func.matched) {
builder_.AST().AddFunction(func.value);
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 add_error(next(), "expected declaration after attributes");
}
// We have a statement outside of a function?
auto& t = peek();
auto stat = without_error([&] { 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 add_error(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*> ParserImpl::global_variable_decl(AttributeList& attrs) {
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 add_error(peek(), "missing initializer for 'var' declaration");
}
initializer = expr.value;
}
TINT_DEFER(attrs.Clear());
return create<ast::Var>(decl->source, // source
builder_.Symbols().Register(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*> ParserImpl::global_constant_decl(AttributeList& attrs) {
bool is_const = false;
bool is_overridable = false;
const char* use = nullptr;
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 add_error(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 add_error(peek(), "missing initializer for " + std::string(use));
}
initializer = std::move(expr.value);
}
TINT_DEFER(attrs.Clear());
if (is_const) {
return create<ast::Const>(decl->source, // source
builder_.Symbols().Register(decl->name), // symbol
decl->type, // type
initializer, // initializer
std::move(attrs)); // attributes
}
if (is_overridable) {
return create<ast::Override>(decl->source, // source
builder_.Symbols().Register(decl->name), // symbol
decl->type, // type
initializer, // initializer
std::move(attrs)); // attributes
}
return create<ast::Const>(decl->source, // source
builder_.Symbols().Register(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<ParserImpl::VarDeclInfo> ParserImpl::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->source, decl->name, vq.address_space, vq.access, decl->type};
}
// texture_and_sampler_types
// : sampler_type
// | depth_texture_type
// | sampled_texture_type LESS_THAN type_specifier GREATER_THAN
// | multisampled_texture_type LESS_THAN type_specifier GREATER_THAN
// | storage_texture_type LESS_THAN texel_format
// COMMA access_mode GREATER_THAN
Maybe<const ast::Type*> ParserImpl::texture_and_sampler_types() {
auto type = sampler_type();
if (type.matched) {
return type;
}
type = depth_texture_type();
if (type.matched) {
return type;
}
type = external_texture();
if (type.matched) {
return type.value;
}
auto source_range = make_source_range();
auto dim = sampled_texture_type();
if (dim.matched) {
const char* use = "sampled texture type";
auto subtype = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (subtype.errored) {
return Failure::kErrored;
}
return builder_.ty.sampled_texture(source_range, dim.value, subtype.value);
}
auto ms_dim = multisampled_texture_type();
if (ms_dim.matched) {
const char* use = "multisampled texture type";
auto subtype = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (subtype.errored) {
return Failure::kErrored;
}
return builder_.ty.multisampled_texture(source_range, ms_dim.value, subtype.value);
}
auto storage = storage_texture_type();
if (storage.matched) {
const char* use = "storage texture type";
using StorageTextureInfo = std::pair<tint::ast::TexelFormat, tint::ast::Access>;
auto params = expect_lt_gt_block(use, [&]() -> Expect<StorageTextureInfo> {
auto format = expect_texel_format(use);
if (format.errored) {
return Failure::kErrored;
}
if (!expect("access control", Token::Type::kComma)) {
return Failure::kErrored;
}
auto access = expect_access_mode(use);
if (access.errored) {
return Failure::kErrored;
}
return std::make_pair(format.value, access.value);
});
if (params.errored) {
return Failure::kErrored;
}
return builder_.ty.storage_texture(source_range, storage.value, params->first,
params->second);
}
return Failure::kNoMatch;
}
// sampler_type
// : SAMPLER
// | SAMPLER_COMPARISON
Maybe<const ast::Type*> ParserImpl::sampler_type() {
Source source;
if (match(Token::Type::kSampler, &source)) {
return builder_.ty.sampler(source, ast::SamplerKind::kSampler);
}
if (match(Token::Type::kComparisonSampler, &source)) {
return builder_.ty.sampler(source, ast::SamplerKind::kComparisonSampler);
}
return Failure::kNoMatch;
}
// sampled_texture_type
// : TEXTURE_SAMPLED_1D
// | TEXTURE_SAMPLED_2D
// | TEXTURE_SAMPLED_2D_ARRAY
// | TEXTURE_SAMPLED_3D
// | TEXTURE_SAMPLED_CUBE
// | TEXTURE_SAMPLED_CUBE_ARRAY
Maybe<const ast::TextureDimension> ParserImpl::sampled_texture_type() {
if (match(Token::Type::kTextureSampled1d)) {
return ast::TextureDimension::k1d;
}
if (match(Token::Type::kTextureSampled2d)) {
return ast::TextureDimension::k2d;
}
if (match(Token::Type::kTextureSampled2dArray)) {
return ast::TextureDimension::k2dArray;
}
if (match(Token::Type::kTextureSampled3d)) {
return ast::TextureDimension::k3d;
}
if (match(Token::Type::kTextureSampledCube)) {
return ast::TextureDimension::kCube;
}
if (match(Token::Type::kTextureSampledCubeArray)) {
return ast::TextureDimension::kCubeArray;
}
return Failure::kNoMatch;
}
// external_texture
// : TEXTURE_EXTERNAL
Maybe<const ast::Type*> ParserImpl::external_texture() {
Source source;
if (match(Token::Type::kTextureExternal, &source)) {
return builder_.ty.external_texture(source);
}
return Failure::kNoMatch;
}
// multisampled_texture_type
// : TEXTURE_MULTISAMPLED_2D
Maybe<const ast::TextureDimension> ParserImpl::multisampled_texture_type() {
if (match(Token::Type::kTextureMultisampled2d)) {
return ast::TextureDimension::k2d;
}
return Failure::kNoMatch;
}
// storage_texture_type
// : TEXTURE_STORAGE_1D
// | TEXTURE_STORAGE_2D
// | TEXTURE_STORAGE_2D_ARRAY
// | TEXTURE_STORAGE_3D
Maybe<const ast::TextureDimension> ParserImpl::storage_texture_type() {
if (match(Token::Type::kTextureStorage1d)) {
return ast::TextureDimension::k1d;
}
if (match(Token::Type::kTextureStorage2d)) {
return ast::TextureDimension::k2d;
}
if (match(Token::Type::kTextureStorage2dArray)) {
return ast::TextureDimension::k2dArray;
}
if (match(Token::Type::kTextureStorage3d)) {
return ast::TextureDimension::k3d;
}
return Failure::kNoMatch;
}
// depth_texture_type
// : TEXTURE_DEPTH_2D
// | TEXTURE_DEPTH_2D_ARRAY
// | TEXTURE_DEPTH_CUBE
// | TEXTURE_DEPTH_CUBE_ARRAY
// | TEXTURE_DEPTH_MULTISAMPLED_2D
Maybe<const ast::Type*> ParserImpl::depth_texture_type() {
Source source;
if (match(Token::Type::kTextureDepth2d, &source)) {
return builder_.ty.depth_texture(source, ast::TextureDimension::k2d);
}
if (match(Token::Type::kTextureDepth2dArray, &source)) {
return builder_.ty.depth_texture(source, ast::TextureDimension::k2dArray);
}
if (match(Token::Type::kTextureDepthCube, &source)) {
return builder_.ty.depth_texture(source, ast::TextureDimension::kCube);
}
if (match(Token::Type::kTextureDepthCubeArray, &source)) {
return builder_.ty.depth_texture(source, ast::TextureDimension::kCubeArray);
}
if (match(Token::Type::kTextureDepthMultisampled2d, &source)) {
return builder_.ty.depth_multisampled_texture(source, ast::TextureDimension::k2d);
}
return Failure::kNoMatch;
}
// texel_format
// : 'rgba8unorm'
// | 'rgba8snorm'
// | 'rgba8uint'
// | 'rgba8sint'
// | 'rgba16uint'
// | 'rgba16sint'
// | 'rgba16float'
// | 'r32uint'
// | 'r32sint'
// | 'r32float'
// | 'rg32uint'
// | 'rg32sint'
// | 'rg32float'
// | 'rgba32uint'
// | 'rgba32sint'
// | 'rgba32float'
Expect<ast::TexelFormat> ParserImpl::expect_texel_format(std::string_view use) {
return expect_enum("texel format", ast::ParseTexelFormat, ast::kTexelFormatStrings, use);
}
Expect<ParserImpl::TypedIdentifier> ParserImpl::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{nullptr, ident.value, ident.source};
}
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 add_error(t.source(), "invalid type", use);
}
return TypedIdentifier{type.value, ident.value, ident.source};
}
// optionally_typed_ident
// : ident ( COLON typed_decl ) ?
Expect<ParserImpl::TypedIdentifier> ParserImpl::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<ParserImpl::TypedIdentifier> ParserImpl::expect_ident_with_type_specifier(
std::string_view use) {
return expect_ident_with_optional_type_specifier(use, /* allow_inferred */ false);
}
// access_mode
// : 'read'
// | 'write'
// | 'read_write'
Expect<ast::Access> ParserImpl::expect_access_mode(std::string_view use) {
return expect_enum("access control", ast::ParseAccess, ast::kAccessStrings, use);
}
// variable_qualifier
// : LESS_THAN address_spaces (COMMA access_mode)? GREATER_THAN
Maybe<ParserImpl::VariableQualifier> ParserImpl::variable_qualifier() {
if (!peek_is(Token::Type::kLessThan)) {
return Failure::kNoMatch;
}
auto* use = "variable declaration";
auto vq = expect_lt_gt_block(use, [&]() -> Expect<VariableQualifier> {
auto source = make_source_range();
auto sc = expect_address_space(use);
if (sc.errored) {
return Failure::kErrored;
}
if (match(Token::Type::kComma)) {
auto ac = expect_access_mode(use);
if (ac.errored) {
return Failure::kErrored;
}
return VariableQualifier{sc.value, ac.value};
}
return Expect<VariableQualifier>{VariableQualifier{sc.value, ast::Access::kUndefined},
source};
});
if (vq.errored) {
return Failure::kErrored;
}
return vq;
}
// type_alias_decl
// : TYPE IDENT EQUAL type_specifier
Maybe<const ast::Alias*> ParserImpl::type_alias_decl() {
if (!peek_is(Token::Type::kType)) {
return Failure::kNoMatch;
}
auto& t = next();
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 add_error(peek(), "invalid type alias");
}
return builder_.ty.alias(make_source_range_from(t.source()), name.value, type.value);
}
// vec_prefix
// : 'vec2'
// | 'vec3'
// | 'vec4'
Maybe<uint32_t> ParserImpl::vec_prefix() {
auto& t = peek();
if (!t.IsVector()) {
return Failure::kNoMatch;
}
next();
if (t.Is(Token::Type::kVec3)) {
return 3u;
}
if (t.Is(Token::Type::kVec4)) {
return 4u;
}
return 2u;
}
// mat_prefix
// : 'mat2x2'
// | 'mat2x3'
// | 'mat2x4'
// | 'mat3x2'
// | 'mat3x3'
// | 'mat3x4'
// | 'mat4x2'
// | 'mat4x3'
// | 'mat4x4'
Maybe<ParserImpl::MatrixDimensions> ParserImpl::mat_prefix() {
auto& t = peek();
if (!t.IsMatrix()) {
return Failure::kNoMatch;
}
next();
uint32_t columns = 2;
if (t.IsMat3xN()) {
columns = 3;
} else if (t.IsMat4xN()) {
columns = 4;
}
if (t.IsMatNx3()) {
return MatrixDimensions{columns, 3};
}
if (t.IsMatNx4()) {
return MatrixDimensions{columns, 4};
}
return MatrixDimensions{columns, 2};
}
// type_specifier_without_ident:
// : BOOL
// | F16
// | F32
// | I32
// | U32
// | ARRAY LESS_THAN type_specifier ( COMMA element_count_expression )? GREATER_THAN
// | ATOMIC LESS_THAN type_specifier GREATER_THAN
// | PTR LESS_THAN address_space COMMA type_specifier ( COMMA access_mode )? GREATER_THAN
// | mat_prefix LESS_THAN type_specifier GREATER_THAN
// | vec_prefix LESS_THAN type_specifier GREATER_THAN
// | texture_and_sampler_types
Maybe<const ast::Type*> ParserImpl::type_specifier_without_ident() {
auto& t = peek();
if (match(Token::Type::kBool)) {
return builder_.ty.bool_(t.source());
}
if (match(Token::Type::kF16)) {
return builder_.ty.f16(t.source());
}
if (match(Token::Type::kF32)) {
return builder_.ty.f32(t.source());
}
if (match(Token::Type::kI32)) {
return builder_.ty.i32(t.source());
}
if (match(Token::Type::kU32)) {
return builder_.ty.u32(t.source());
}
if (t.Is(Token::Type::kArray) && peek_is(Token::Type::kLessThan, 1)) {
if (match(Token::Type::kArray)) {
return expect_type_specifier_array(t.source());
}
}
if (match(Token::Type::kAtomic)) {
return expect_type_specifier_atomic(t.source());
}
if (match(Token::Type::kPtr)) {
return expect_type_specifier_pointer(t.source());
}
if (t.IsMatrix() && peek_is(Token::Type::kLessThan, 1)) {
auto mat = mat_prefix();
if (mat.matched) {
return expect_type_specifier_matrix(t.source(), mat.value);
}
}
if (t.IsVector() && peek_is(Token::Type::kLessThan, 1)) {
auto vec = vec_prefix();
if (vec.matched) {
return expect_type_specifier_vector(t.source(), vec.value);
}
}
auto texture_or_sampler = texture_and_sampler_types();
if (texture_or_sampler.errored) {
return Failure::kErrored;
}
if (texture_or_sampler.matched) {
return texture_or_sampler;
}
return Failure::kNoMatch;
}
// type_specifier
// : IDENTIFIER
// | type_specifier_without_ident
Maybe<const ast::Type*> ParserImpl::type_specifier() {
auto& t = peek();
Source source;
if (match(Token::Type::kIdentifier, &source)) {
return builder_.create<ast::TypeName>(source, builder_.Symbols().Register(t.to_str()));
}
return type_specifier_without_ident();
}
template <typename ENUM, size_t N>
Expect<ENUM> ParserImpl::expect_enum(std::string_view name,
ENUM (*parse)(std::string_view str),
const char* const (&strings)[N],
std::string_view use) {
auto& t = peek();
if (t.IsIdentifier()) {
auto val = parse(t.to_str());
if (val != ENUM::kUndefined) {
synchronized_ = true;
next();
return {val, t.source()};
}
}
// Was the token itself an error?
if (handle_error(t)) {
return Failure::kErrored;
}
/// Create a sensible error message
std::stringstream err;
err << "expected " << name;
if (!use.empty()) {
err << " for " << use;
}
// If the string typed was within kSuggestionDistance of one of the possible enum values,
// suggest that. Don't bother with suggestions if the string was extremely long.
constexpr size_t kSuggestionDistance = 5;
constexpr size_t kSuggestionMaxLength = 64;
if (auto got = t.to_str(); !got.empty() && got.size() < kSuggestionMaxLength) {
size_t candidate_dist = kSuggestionDistance;
const char* candidate = nullptr;
for (auto* str : strings) {
auto dist = utils::Distance(str, got);
if (dist < candidate_dist) {
candidate = str;
candidate_dist = dist;
}
}
if (candidate) {
err << ". Did you mean '" << candidate << "'?";
}
}
// List all the possible enumerator values
err << "\nPossible values: ";
for (auto* str : strings) {
if (str != strings[0]) {
err << ", ";
}
err << "'" << str << "'";
}
synchronized_ = false;
return add_error(t.source(), err.str());
}
Expect<const ast::Type*> ParserImpl::expect_type(std::string_view use) {
auto type = type_specifier();
if (type.errored) {
return Failure::kErrored;
}
if (!type.matched) {
return add_error(peek().source(), "invalid type", use);
}
return type.value;
}
// LESS_THAN address_space COMMA type_specifier ( COMMA access_mode )? GREATER_THAN
Expect<const ast::Type*> ParserImpl::expect_type_specifier_pointer(const Source& s) {
const char* use = "ptr declaration";
auto address_space = ast::AddressSpace::kNone;
auto access = ast::Access::kUndefined;
auto subtype = expect_lt_gt_block(use, [&]() -> Expect<const ast::Type*> {
auto sc = expect_address_space(use);
if (sc.errored) {
return Failure::kErrored;
}
address_space = sc.value;
if (!expect(use, Token::Type::kComma)) {
return Failure::kErrored;
}
auto type = expect_type(use);
if (type.errored) {
return Failure::kErrored;
}
if (match(Token::Type::kComma)) {
auto ac = expect_access_mode(use);
if (ac.errored) {
return Failure::kErrored;
}
access = ac.value;
}
return type.value;
});
if (subtype.errored) {
return Failure::kErrored;
}
return builder_.ty.pointer(make_source_range_from(s), subtype.value, address_space, access);
}
// LESS_THAN type_specifier GREATER_THAN
Expect<const ast::Type*> ParserImpl::expect_type_specifier_atomic(const Source& s) {
const char* use = "atomic declaration";
auto subtype = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (subtype.errored) {
return Failure::kErrored;
}
return builder_.ty.atomic(make_source_range_from(s), subtype.value);
}
// LESS_THAN type_specifier GREATER_THAN
Expect<const ast::Type*> ParserImpl::expect_type_specifier_vector(const Source& s, uint32_t count) {
const char* use = "vector";
auto ty = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (ty.errored) {
return Failure::kErrored;
}
return builder_.ty.vec(make_source_range_from(s), ty.value, count);
}
// LESS_THAN type_specifier ( COMMA element_count_expression )? GREATER_THAN
Expect<const ast::Type*> ParserImpl::expect_type_specifier_array(const Source& s) {
const char* use = "array declaration";
struct TypeAndSize {
const ast::Type* type = nullptr;
const ast::Expression* size = nullptr;
};
if (!peek_is(Token::Type::kLessThan)) {
return add_error(peek(), "expected < for array");
}
auto type_size = expect_lt_gt_block(use, [&]() -> Expect<TypeAndSize> {
auto type = expect_type(use);
if (type.errored) {
return Failure::kErrored;
}
if (!match(Token::Type::kComma)) {
return TypeAndSize{type.value, nullptr};
}
auto size = element_count_expression();
if (size.errored) {
return Failure::kErrored;
}
if (!size.matched) {
return add_error(peek(), "expected array size expression");
}
return TypeAndSize{type.value, size.value};
});
if (type_size.errored) {
return Failure::kErrored;
}
return builder_.ty.array(make_source_range_from(s), type_size->type, type_size->size);
}
// LESS_THAN type_specifier GREATER_THAN
Expect<const ast::Type*> ParserImpl::expect_type_specifier_matrix(const Source& s,
const MatrixDimensions& dims) {
const char* use = "matrix";
auto ty = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (ty.errored) {
return Failure::kErrored;
}
return builder_.ty.mat(make_source_range_from(s), ty.value, dims.columns, dims.rows);
}
// address_space
// : 'function'
// | 'private'
// | 'workgroup'
// | 'uniform'
// | 'storage'
//
// Note, we also parse `push_constant` from the experimental extension
Expect<ast::AddressSpace> ParserImpl::expect_address_space(std::string_view use) {
return expect_enum("address space", ast::ParseAddressSpace, ast::kAddressSpaceStrings, use);
}
// struct_decl
// : STRUCT IDENT struct_body_decl
Maybe<const ast::Struct*> ParserImpl::struct_decl() {
auto& t = peek();
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;
}
auto sym = builder_.Symbols().Register(name.value);
return create<ast::Struct>(t.source(), sym, std::move(body.value), utils::Empty);
}
// struct_body_decl
// : BRACE_LEFT (struct_member COMMA)* struct_member COMMA? BRACE_RIGHT
Expect<ParserImpl::StructMemberList> ParserImpl::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<ast::StructMember*> ParserImpl::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 create<ast::StructMember>(decl->source, builder_.Symbols().Register(decl->name),
decl->type, std::move(attrs.value));
}
// static_assert_statement
// : STATIC_ASSERT expression
Maybe<const ast::StaticAssert*> ParserImpl::static_assert_statement() {
Source start;
if (!match(Token::Type::kStaticAssert, &start)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return add_error(peek(), "unable to parse condition expression");
}
Source source = make_source_range_from(start);
return create<ast::StaticAssert>(source, condition.value);
}
// function_decl
// : function_header compound_statement
Maybe<const ast::Function*> ParserImpl::function_decl(AttributeList& attrs) {
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();
}
return Failure::kErrored;
}
if (!header.matched) {
return Failure::kNoMatch;
}
bool errored = false;
auto body = expect_compound_statement();
if (body.errored) {
errored = true;
}
if (errored) {
return Failure::kErrored;
}
TINT_DEFER(attrs.Clear());
return create<ast::Function>(header->source, builder_.Symbols().Register(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<ParserImpl::FunctionHeader> ParserImpl::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;
}
}
const ast::Type* return_type = nullptr;
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 add_error(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, std::move(name.value), std::move(params.value),
return_type, std::move(return_attributes),
};
}
// param_list
// :
// | (param COMMA)* param COMMA?
Expect<ParserImpl::ParameterList> ParserImpl::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<ast::Parameter*> ParserImpl::expect_param() {
auto attrs = attribute_list();
auto decl = expect_ident_with_type_specifier("parameter");
if (decl.errored) {
return Failure::kErrored;
}
return create<ast::Parameter>(decl->source, // source
builder_.Symbols().Register(decl->name), // symbol
decl->type, // type
std::move(attrs.value)); // attributes
}
// interpolation_sample_name
// : 'center'
// | 'centroid'
// | 'sample'
Expect<ast::InterpolationSampling> ParserImpl::expect_interpolation_sample_name() {
return expect_enum("interpolation sampling", ast::ParseInterpolationSampling,
ast::kInterpolationSamplingStrings);
}
// interpolation_type_name
// : 'perspective'
// | 'linear'
// | 'flat'
Expect<ast::InterpolationType> ParserImpl::expect_interpolation_type_name() {
return expect_enum("interpolation type", ast::ParseInterpolationType,
ast::kInterpolationTypeStrings);
}
// builtin_value_name
// : frag_depth
// | front_facing
// | global_invocation_id
// | instance_index
// | local_invocation_id
// | local_invocation_index
// | num_workgroups
// | position
// | sample_index
// | sample_mask
// | vertex_index
// | workgroup_id
Expect<ast::BuiltinValue> ParserImpl::expect_builtin() {
return expect_enum("builtin", ast::ParseBuiltinValue, ast::kBuiltinValueStrings);
}
// compound_statement
// : BRACE_LEFT statement* BRACE_RIGHT
Expect<ast::BlockStatement*> ParserImpl::expect_compound_statement() {
return expect_brace_block("", [&]() -> Expect<ast::BlockStatement*> {
auto stmts = expect_statements();
if (stmts.errored) {
return Failure::kErrored;
}
return create<ast::BlockStatement>(Source{}, stmts.value);
});
}
// paren_expression
// : PAREN_LEFT expression PAREN_RIGHT
Expect<const ast::Expression*> ParserImpl::expect_paren_expression() {
return expect_paren_block("", [&]() -> Expect<const ast::Expression*> {
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
if (!expr.matched) {
return add_error(peek(), "unable to parse expression");
}
return expr.value;
});
}
// statements
// : statement*
Expect<ParserImpl::StatementList> ParserImpl::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*> ParserImpl::statement() {
while (match(Token::Type::kSemicolon)) {
// Skip empty statements
}
// 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();
if (stmt_if.errored) {
return Failure::kErrored;
}
if (stmt_if.matched) {
return stmt_if.value;
}
auto sw = switch_statement();
if (sw.errored) {
return Failure::kErrored;
}
if (sw.matched) {
return sw.value;
}
auto loop = loop_statement();
if (loop.errored) {
return Failure::kErrored;
}
if (loop.matched) {
return loop.value;
}
auto stmt_for = for_statement();
if (stmt_for.errored) {
return Failure::kErrored;
}
if (stmt_for.matched) {
return stmt_for.value;
}
auto stmt_while = while_statement();
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();
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
// | static_assert_statement SEMICOLON
Maybe<const ast::Statement*> ParserImpl::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 create<ast::DiscardStatement>(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 = static_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*> ParserImpl::return_statement() {
Source source;
if (!match(Token::Type::kReturn, &source)) {
return Failure::kNoMatch;
}
if (peek_is(Token::Type::kSemicolon)) {
return create<ast::ReturnStatement>(source, nullptr);
}
auto expr = expression();
if (expr.errored) {
return Failure::kErrored;
}
// TODO(bclayton): Check matched?
return create<ast::ReturnStatement>(source, expr.value);
}
// variable_statement
// : variable_decl
// | variable_decl EQUAL expression
// | LET optionally_typed_ident EQUAL expression
// | CONST optionally_typed_ident EQUAL expression
Maybe<const ast::VariableDeclStatement*> ParserImpl::variable_statement() {
auto decl_source_range = make_source_range();
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.Source();
if (!expect("'const' declaration", Token::Type::kEqual)) {
return Failure::kErrored;
}
auto initializer = expression();
if (initializer.errored) {
return Failure::kErrored;
}
if (!initializer.matched) {
return add_error(peek(), "missing initializer for 'const' declaration");
}
auto* const_ = create<ast::Const>(typed_ident->source, // source
builder_.Symbols().Register(typed_ident->name), // symbol
typed_ident->type, // type
initializer.value, // initializer
utils::Empty); // attributes
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.Source();
if (!expect("'let' declaration", Token::Type::kEqual)) {
return Failure::kErrored;
}
auto initializer = expression();
if (initializer.errored) {
return Failure::kErrored;
}
if (!initializer.matched) {
return add_error(peek(), "missing initializer for 'let' declaration");
}
auto* let = create<ast::Let>(typed_ident->source, // source
builder_.Symbols().Register(typed_ident->name), // symbol
typed_ident->type, // type
initializer.value, // initializer
utils::Empty); // attributes
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.Source();
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 add_error(peek(), "missing initializer for 'var' declaration");
}
initializer = initializer_expr.value;
}
auto* var = create<ast::Var>(decl_source, // source
builder_.Symbols().Register(decl->name), // symbol
decl->type, // type
decl->address_space, // address space
decl->access, // access control
initializer, // initializer
utils::Empty); // attributes
return create<ast::VariableDeclStatement>(var->source, var);
}
// if_statement
// : IF expression compound_stmt ( ELSE else_stmt ) ?
// else_stmt
// : compound_statement
// | if_statement
Maybe<const ast::IfStatement*> ParserImpl::if_statement() {
// 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;
};
// 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 add_error(peek(), "unable to parse condition expression");
}
auto body = expect_compound_statement();
if (body.errored) {
return Failure::kErrored;
}
return IfInfo{source, condition.value, body.value};
};
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();
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);
}
return last_stmt->As<ast::IfStatement>();
}
// switch_statement
// : SWITCH expression BRACKET_LEFT switch_body+ BRACKET_RIGHT
Maybe<const ast::SwitchStatement*> ParserImpl::switch_statement() {
Source source;
if (!match(Token::Type::kSwitch, &source)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return add_error(peek(), "unable to parse selector expression");
}
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;
}
return create<ast::SwitchStatement>(source, condition.value, body.value);
}
// switch_body
// : CASE case_selectors COLON? BRACKET_LEFT case_body BRACKET_RIGHT
// | DEFAULT COLON? BRACKET_LEFT case_body BRACKET_RIGHT
Maybe<const ast::CaseStatement*> ParserImpl::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_brace_block(use, [&] { return case_body(); });
if (body.errored) {
return Failure::kErrored;
}
if (!body.matched) {
return add_error(body.source, "expected case body");
}
return create<ast::CaseStatement>(t.source(), selector_list, body.value);
}
// case_selectors
// : case_selector (COMMA case_selector)* COMMA?
Expect<ParserImpl::CaseSelectorList> ParserImpl::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 add_error(peek(), "expected case selector expression or `default`");
}
return selectors;
}
// case_selector
// : DEFAULT
// | expression
Maybe<const ast::CaseSelector*> ParserImpl::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);
}
// case_body
// :
// | statement case_body
Maybe<const ast::BlockStatement*> ParserImpl::case_body() {
StatementList stmts;
while (continue_parsing()) {
Source source;
if (match(Token::Type::kFallthrough, &source)) {
return add_error(
source,
"fallthrough is not premitted in WGSL. "
"Case can accept multiple selectors if the existing case bodies are empty. "
"(e.g. `case 1, 2, 3:`) "
"`default` is a valid case selector value. (e.g. `case 1, default:`)");
}
auto stmt = statement();
if (stmt.errored) {
return Failure::kErrored;
}
if (!stmt.matched) {
break;
}
stmts.Push(stmt.value);
}
return create<ast::BlockStatement>(Source{}, stmts);
}
// loop_statement
// : LOOP BRACKET_LEFT statements continuing_statement? BRACKET_RIGHT
Maybe<const ast::LoopStatement*> ParserImpl::loop_statement() {
Source source;
if (!match(Token::Type::kLoop, &source)) {
return Failure::kNoMatch;
}
return expect_brace_block("loop", [&]() -> Maybe<const ast::LoopStatement*> {
auto stmts = expect_statements();
if (stmts.errored) {
return Failure::kErrored;
}
auto continuing = continuing_statement();
if (continuing.errored) {
return Failure::kErrored;
}
auto* body = create<ast::BlockStatement>(source, stmts.value);
return create<ast::LoopStatement>(source, body, continuing.value);
});
}
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*> ParserImpl::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*> ParserImpl::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>> ParserImpl::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 BRACE_LEFT statements BRACE_RIGHT
Maybe<const ast::ForLoopStatement*> ParserImpl::for_statement() {
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 stmts = expect_brace_block("for loop", [&] { return expect_statements(); });
if (stmts.errored) {
return Failure::kErrored;
}
return create<ast::ForLoopStatement>(source, header->initializer, header->condition,
header->continuing,
create<ast::BlockStatement>(stmts.value));
}
// while_statement
// : WHILE expression compound_statement
Maybe<const ast::WhileStatement*> ParserImpl::while_statement() {
Source source;
if (!match(Token::Type::kWhile, &source)) {
return Failure::kNoMatch;
}
auto condition = expression();
if (condition.errored) {
return Failure::kErrored;
}
if (!condition.matched) {
return add_error(peek(), "unable to parse while condition expression");
}
auto body = expect_compound_statement();
if (body.errored) {
return Failure::kErrored;
}
return create<ast::WhileStatement>(source, condition.value, body.value);
}
// func_call_statement
// : IDENT argument_expression_list
Maybe<const ast::CallStatement*> ParserImpl::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 create<ast::CallStatement>(
t.source(),
create<ast::CallExpression>(
t.source(),
create<ast::IdentifierExpression>(t.source(), builder_.Symbols().Register(t.to_str())),
std::move(params.value)));
}
// break_statement
// : BREAK
Maybe<const ast::BreakStatement*> ParserImpl::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*> ParserImpl::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*> ParserImpl::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 add_error(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:
// brace_left statement* break_if_statement? brace_right
Maybe<const ast::BlockStatement*> ParserImpl::continuing_compound_statement() {
return expect_brace_block("", [&]() -> Expect<ast::BlockStatement*> {
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 create<ast::BlockStatement>(Source{}, stmts);
});
}
// continuing_statement
// : CONTINUING continuing_compound_statement
Maybe<const ast::BlockStatement*> ParserImpl::continuing_statement() {
if (!match(Token::Type::kContinuing)) {
return create<ast::BlockStatement>(Source{}, utils::Empty);
}
return continuing_compound_statement();
}
// callable
// : type_specifier_without_ident
// | ARRAY
// | mat_prefix
// | vec_prefix
//
// Note, `ident` is pulled out to `primary_expression` as it's the only one that
// doesn't create a `type`. Then we can just return a `type` from here on match and
// deal with `ident` in `primary_expression.
Maybe<const ast::Type*> ParserImpl::callable() {
auto& t = peek();
// This _must_ match `type_specifier_without_ident` before any of the other types as they're
// all prefixes of the types and we want to match the longer `vec3<f32>` then the shorter
// prefix match of `vec3`.
auto ty = type_specifier_without_ident();
if (ty.errored) {
return Failure::kErrored;
}
if (ty.matched) {
return ty.value;
}
if (match(Token::Type::kArray)) {
return builder_.ty.array(make_source_range_from(t.source()), nullptr, nullptr);
}
auto vec = vec_prefix();
if (vec.matched) {
return builder_.ty.vec(make_source_range_from(t.source()), nullptr, vec.value);
}
auto mat = mat_prefix();
if (mat.matched) {
return builder_.ty.mat(make_source_range_from(t.source()), nullptr, mat.value.columns,
mat.value.rows);
}
return Failure::kNoMatch;
}
// primary_expression
// : BITCAST LESS_THAN type_specifier GREATER_THAN paren_expression
// | callable argument_expression_list
// | const_literal
// | IDENT argument_expression_list?
// | paren_expression
//
// Note, PAREN_LEFT ( expression ( COMMA expression ) * COMMA? )? PAREN_RIGHT is replaced
// with `argument_expression_list`.
//
// Note, this is matching the `callable` ident here instead of having to come from
// callable so we can return a `type` from callable.
Maybe<const ast::Expression*> ParserImpl::primary_expression() {
auto& t = peek();
if (match(Token::Type::kBitcast)) {
const char* use = "bitcast expression";
auto type = expect_lt_gt_block(use, [&] { return expect_type(use); });
if (type.errored) {
return Failure::kErrored;
}
auto params = expect_paren_expression();
if (params.errored) {
return Failure::kErrored;
}
return create<ast::BitcastExpression>(t.source(), type.value, params.value);
}
auto call = callable();
if (call.errored) {
return Failure::kErrored;
}
if (call.matched) {
auto params = expect_argument_expression_list("type initializer");
if (params.errored) {
return Failure::kErrored;
}
return builder_.Construct(t.source(), call.value, std::move(params.value));
}
auto lit = const_literal();
if (lit.errored) {
return Failure::kErrored;
}
if (lit.matched) {
return lit.value;
}
if (t.IsIdentifier()) {
next();
auto* ident =
create<ast::IdentifierExpression>(t.source(), builder_.Symbols().Register(t.to_str()));
if (peek_is(Token::Type::kParenLeft)) {
auto params = expect_argument_expression_list("function call");
if (params.errored) {
return Failure::kErrored;
}
return create<ast::CallExpression>(t.source(), ident, std::move(params.value));
}
return 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*> ParserImpl::component_or_swizzle_specifier(
const ast::Expression* prefix) {
Source source;
while (continue_parsing()) {
if (match(Token::Type::kBracketLeft, &source)) {
auto res = sync(Token::Type::kBracketRight, [&]() -> Maybe<const ast::Expression*> {
auto param = expression();
if (param.errored) {
return Failure::kErrored;
}
if (!param.matched) {
return add_error(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 = create<ast::MemberAccessorExpression>(
ident.source, prefix,
create<ast::IdentifierExpression>(ident.source,
builder_.Symbols().Register(ident.value)));
continue;
}
return prefix;
}
return Failure::kErrored;
}
// argument_expression_list
// : PAREN_LEFT ((expression COMMA)* expression COMMA?)? PAREN_RIGHT
Expect<ParserImpl::ExpressionList> ParserImpl::expect_argument_expression_list(
std::string_view use) {
return expect_paren_block(use, [&]() -> Expect<ExpressionList> {
ExpressionList ret;
while (continue_parsing()) {
auto arg = expression();
if (arg.errored) {
return Failure::kErrored;
} else if (!arg.matched) {
break;
}
ret.Push(arg.value);
if (!match(Token::Type::kComma)) {
break;
}
}
return ret;
});
}
// 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*> ParserImpl::bitwise_expression_post_unary_expression(
const ast::Expression* lhs) {
auto& t = peek();
ast::BinaryOp op = ast::BinaryOp::kXor;
switch (t.type()) {
case Token::Type::kAnd:
op = ast::BinaryOp::kAnd;
break;
case Token::Type::kOr:
op = ast::BinaryOp::kOr;
break;
case Token::Type::kXor:
op = ast::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 add_error(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
lhs = create<ast::BinaryExpression>(t.source(), op, lhs, rhs.value);
if (!match(t.type())) {
return lhs;
}
}
return Failure::kErrored;
}
// multiplicative_operator
// : FORWARD_SLASH
// | MODULO
// | STAR
Maybe<ast::BinaryOp> ParserImpl::multiplicative_operator() {
if (match(Token::Type::kForwardSlash)) {
return ast::BinaryOp::kDivide;
}
if (match(Token::Type::kMod)) {
return ast::BinaryOp::kModulo;
}
if (match(Token::Type::kStar)) {
return ast::BinaryOp::kMultiply;
}
return Failure::kNoMatch;
}
// multiplicative_expression.post.unary_expression
// : (multiplicative_operator unary_expression)*
Expect<const ast::Expression*> ParserImpl::expect_multiplicative_expression_post_unary_expression(
const ast::Expression* lhs) {
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 add_error(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
lhs = create<ast::BinaryExpression>(t.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<ast::BinaryOp> ParserImpl::additive_operator() {
if (match(Token::Type::kPlus)) {
return ast::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 ast::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*> ParserImpl::expect_additive_expression_post_unary_expression(
const ast::Expression* lhs) {
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 add_error(peek(), std::string("unable to parse right side of ") +
std::string(t.to_name()) + " expression");
}
// The multiplicative binds tigher, so pass the unary into that and build that expression
// before creating the additve expression.
auto rhs = expect_multiplicative_expression_post_unary_expression(unary.value);
if (rhs.errored) {
return Failure::kErrored;
}
lhs = create<ast::BinaryExpression>(t.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*> ParserImpl::expect_math_expression_post_unary_expression(
const ast::Expression* lhs) {
auto rhs = expect_multiplicative_expression_post_unary_expression(lhs);
if (rhs.errored) {
return Failure::kErrored;
}
return expect_additive_expression_post_unary_expression(rhs.value);
}
// element_count_expression
// : unary_expression math_expression.post.unary_expression
// | unary_expression bitwise_expression.post.unary_expression
//
// Note, this moves the `( multiplicative_operator unary_expression )* ( additive_operator
// unary_expression ( multiplicative_operator unary_expression )* )*` expression for the first
// branch out into helper methods.
Maybe<const ast::Expression*> ParserImpl::element_count_expression() {
auto lhs = unary_expression();