Revert "Revert "Revert "Switched highp float to highfloat and mediump float to half."""

This reverts commit 05d5a13fea6246648de7e41358ed338d53c85ea2.

Reason for revert: looks like it broke filterfastbounds

Original change's description:
> Revert "Revert "Switched highp float to highfloat and mediump float to half.""
> 
> This reverts commit 1d816b92bb7cf2258007f3f74ffd143b89f25d01.
> 
> Bug: skia:
> Change-Id: I388b5e5e9bf619db48297a80c9a80c039f26c9f1
> Reviewed-on: https://skia-review.googlesource.com/46464
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

TBR=bsalomon@google.com,ethannicholas@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:
Change-Id: Iddf6aef2ab084aa73da7ceebdfc303a1d2b80cde
Reviewed-on: https://skia-review.googlesource.com/47441
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

1 files changed, 39 insertions, 1 deletions

diff --git a/src/sksl/SkSLParser.cpp b/src/sksl/SkSLParser.cpp
index 9bfa62f2f5..d8ecc618bc 100644
--- a/src/sksl/SkSLParser.cpp
+++ b/src/sksl/SkSLParser.cpp
@@ -29,6 +29,7 @@
 #include "ast/SkSLASTIntLiteral.h"
 #include "ast/SkSLASTModifiersDeclaration.h"
 #include "ast/SkSLASTParameter.h"
+#include "ast/SkSLASTPrecision.h"
 #include "ast/SkSLASTPrefixExpression.h"
 #include "ast/SkSLASTReturnStatement.h"
 #include "ast/SkSLASTSection.h"
@@ -80,13 +81,20 @@ Parser::Parser(const char* text, size_t length, SymbolTable& types, ErrorReporte
     fLexer.start(text, length);
 }
 
-/* (directive | section | declaration)* END_OF_FILE */
+/* (precision | directive | section | declaration)* END_OF_FILE */
 std::vector<std::unique_ptr<ASTDeclaration>> Parser::file() {
     std::vector<std::unique_ptr<ASTDeclaration>> result;
     for (;;) {
         switch (this->peek().fKind) {
             case Token::END_OF_FILE:
                 return result;
+            case Token::PRECISION: {
+                std::unique_ptr<ASTDeclaration> precision = this->precision();
+                if (precision) {
+                    result.push_back(std::move(precision));
+                }
+                break;
+            }
             case Token::DIRECTIVE: {
                 std::unique_ptr<ASTDeclaration> decl = this->directive();
                 if (decl) {
@@ -188,6 +196,36 @@ bool Parser::isType(StringFragment name) {
     return nullptr != fTypes[name];
 }
 
+/* PRECISION (LOWP | MEDIUMP | HIGHP) type SEMICOLON */
+std::unique_ptr<ASTDeclaration> Parser::precision() {
+    if (!this->expect(Token::PRECISION, "'precision'")) {
+        return nullptr;
+    }
+    Modifiers::Flag result;
+    Token p = this->nextToken();
+    switch (p.fKind) {
+        case Token::LOWP:
+            result = Modifiers::kLowp_Flag;
+            break;
+        case Token::MEDIUMP:
+            result = Modifiers::kMediump_Flag;
+            break;
+        case Token::HIGHP:
+            result = Modifiers::kHighp_Flag;
+            break;
+        default:
+            this->error(p, "expected 'lowp', 'mediump', or 'highp', but found '" +
+                           this->text(p) + "'");
+            return nullptr;
+    }
+    // FIXME handle the type
+    if (!this->type()) {
+        return nullptr;
+    }
+    this->expect(Token::SEMICOLON, "';'");
+    return std::unique_ptr<ASTDeclaration>(new ASTPrecision(p.fOffset, result));
+}
+
 /* DIRECTIVE(#version) INT_LITERAL ("es" | "compatibility")? |
    DIRECTIVE(#extension) IDENTIFIER COLON IDENTIFIER */
 std::unique_ptr<ASTDeclaration> Parser::directive() {