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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package scanner_test
import (
"fmt"
"strings"
"text/scanner"
"unicode"
)
func Example() {
const src = `
// This is scanned code.
if a > 10 {
someParsable = text
}`
var s scanner.Scanner
s.Init(strings.NewReader(src))
s.Filename = "example"
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
fmt.Printf("%s: %s\n", s.Position, s.TokenText())
}
// Output:
// example:3:1: if
// example:3:4: a
// example:3:6: >
// example:3:8: 10
// example:3:11: {
// example:4:2: someParsable
// example:4:15: =
// example:4:17: text
// example:5:1: }
}
func Example_isIdentRune() {
const src = "%var1 var2%"
var s scanner.Scanner
s.Init(strings.NewReader(src))
s.Filename = "default"
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
fmt.Printf("%s: %s\n", s.Position, s.TokenText())
}
fmt.Println()
s.Init(strings.NewReader(src))
s.Filename = "percent"
// treat leading '%' as part of an identifier
s.IsIdentRune = func(ch rune, i int) bool {
return ch == '%' && i == 0 || unicode.IsLetter(ch) || unicode.IsDigit(ch) && i > 0
}
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
fmt.Printf("%s: %s\n", s.Position, s.TokenText())
}
// Output:
// default:1:1: %
// default:1:2: var1
// default:1:7: var2
// default:1:11: %
//
// percent:1:1: %var1
// percent:1:7: var2
// percent:1:11: %
}
func Example_mode() {
const src = `
// Comment begins at column 5.
This line should not be included in the output.
/*
This multiline comment
should be extracted in
its entirety.
*/
`
var s scanner.Scanner
s.Init(strings.NewReader(src))
s.Filename = "comments"
s.Mode ^= scanner.SkipComments // don't skip comments
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
txt := s.TokenText()
if strings.HasPrefix(txt, "//") || strings.HasPrefix(txt, "/*") {
fmt.Printf("%s: %s\n", s.Position, txt)
}
}
// Output:
// comments:2:5: // Comment begins at column 5.
// comments:6:1: /*
// This multiline comment
// should be extracted in
// its entirety.
// */
}
func Example_whitespace() {
// tab-separated values
const src = `aa ab ac ad
ba bb bc bd
ca cb cc cd
da db dc dd`
var (
col, row int
s scanner.Scanner
tsv [4][4]string // large enough for example above
)
s.Init(strings.NewReader(src))
s.Whitespace ^= 1<<'\t' | 1<<'\n' // don't skip tabs and new lines
for tok := s.Scan(); tok != scanner.EOF; tok = s.Scan() {
switch tok {
case '\n':
row++
col = 0
case '\t':
col++
default:
tsv[row][col] = s.TokenText()
}
}
fmt.Print(tsv)
// Output:
// [[aa ab ac ad] [ba bb bc bd] [ca cb cc cd] [da db dc dd]]
}
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