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// Copyright (C) 2014 The Android Open Source Project
//
// 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.
package parser
import (
"unicode"
"unicode/utf8"
"android.googlesource.com/platform/tools/gpu/api/ast"
"android.googlesource.com/platform/tools/gpu/parse"
)
func peekOperator(op string, p *parse.Parser) bool {
scanned := scanOperator(p)
p.Rollback()
return op == scanned
}
func operator(op string, p *parse.Parser, cst *parse.Branch) bool {
scanned := scanOperator(p)
if op != scanned {
p.Rollback()
return false
}
p.ParseLeaf(cst, nil)
return true
}
func requireOperator(op string, p *parse.Parser, cst *parse.Branch) {
if !operator(op, p, cst) {
p.Expected(string(op))
}
}
func scanOperator(p *parse.Parser) string {
for _, op := range ast.Operators {
if p.String(string(op)) {
r, _ := utf8.DecodeLastRuneInString(string(op))
if !unicode.IsLetter(r) || !unicode.IsLetter(p.Peek()) {
return op
}
}
}
return ""
}
// lhs operator expression
func binaryOp(p *parse.Parser, lhs ast.Node) *ast.BinaryOp {
op := scanOperator(p)
if _, found := ast.BinaryOperators[op]; !found {
p.Rollback()
return nil
}
n := &ast.BinaryOp{LHS: lhs, Operator: op}
p.Extend(lhs.Node(), func(p *parse.Parser, cst *parse.Branch) {
n.CST = cst
p.ParseLeaf(cst, nil)
n.RHS = requireExpression(p, cst)
})
return n
}
// operator expression
func unaryOp(p *parse.Parser, cst *parse.Branch) *ast.UnaryOp {
op := scanOperator(p)
if _, found := ast.UnaryOperators[op]; !found {
p.Rollback()
return nil
}
p.ParseLeaf(cst, nil)
n := &ast.UnaryOp{Operator: op}
p.ParseBranch(cst, func(p *parse.Parser, cst *parse.Branch) {
n.CST = cst
n.Expression = requireExpression(p, cst)
})
return n
}
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