/
operator.go
90 lines (81 loc) · 2.11 KB
/
operator.go
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// Copyright (C) 2017 Google Inc.
//
// 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"
"github.com/google/gapid/core/text/parse/cst"
"github.com/google/gapid/gapil/ast"
)
func (p *parser) peekOperator(op string) bool {
scanned := p.scanOperator()
p.Rollback()
return op == scanned
}
func (p *parser) operator(op string, b *cst.Branch) bool {
scanned := p.scanOperator()
if op != scanned {
p.Rollback()
return false
}
p.ParseLeaf(b, nil)
return true
}
func (p *parser) requireOperator(op string, b *cst.Branch) {
if !p.operator(op, b) {
p.Expected(string(op))
}
}
func (p *parser) scanOperator() 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 (p *parser) binaryOp(lhs ast.Node) *ast.BinaryOp {
op := p.scanOperator()
if _, found := ast.BinaryOperators[op]; !found {
p.Rollback()
return nil
}
n := &ast.BinaryOp{LHS: lhs, Operator: op}
p.Extend(p.mappings.CST(lhs), func(b *cst.Branch) {
p.mappings.Add(n, b)
p.ParseLeaf(b, nil)
n.RHS = p.requireExpression(b)
})
return n
}
// operator expression
func (p *parser) unaryOp(b *cst.Branch) *ast.UnaryOp {
op := p.scanOperator()
p.Rollback()
if _, found := ast.UnaryOperators[op]; !found {
return nil
}
n := &ast.UnaryOp{Operator: op}
p.ParseBranch(b, func(b *cst.Branch) {
p.requireOperator(op, b)
p.ParseLeaf(b, nil)
p.mappings.Add(n, b)
n.Expression = p.requireExpression(b)
})
return n
}