writer: Simplify floats when printed
Add `tint::writer::FloatToString()`:
Converts the float `f` to a string using fixed-point notation (not scientific).
The float will be printed with the full precision required to describe the float.
All trailing `0`s will be omitted after the last non-zero fractional number,
unless the fractional is zero, in which case the number will end with `.0`.
Use this for the wgsl, msl and hlsl backends.
Change-Id: If5701136579e4398c31c673942f30e8877e9f813
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/33421
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
diff --git a/src/writer/float_to_string.cc b/src/writer/float_to_string.cc
new file mode 100644
index 0000000..b179ed0
--- /dev/null
+++ b/src/writer/float_to_string.cc
@@ -0,0 +1,37 @@
+// 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/writer/float_to_string.h"
+
+#include <limits>
+#include <sstream>
+
+namespace tint {
+namespace writer {
+
+std::string FloatToString(float f) {
+ std::stringstream ss;
+ ss.flags(ss.flags() | std::ios_base::showpoint | std::ios_base::fixed);
+ ss.precision(std::numeric_limits<float>::max_digits10);
+ ss << f;
+ auto str = ss.str();
+ while (str.length() >= 2 && str[str.size() - 1] == '0' &&
+ str[str.size() - 2] != '.') {
+ str.pop_back();
+ }
+ return str;
+}
+
+} // namespace writer
+} // namespace tint
