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94 lines
1.7 KiB
94 lines
1.7 KiB
package syntax
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import (
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"bytes"
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"strconv"
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"strings"
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"unicode"
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)
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func Escape(input string) string {
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b := &bytes.Buffer{}
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for _, r := range input {
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escape(b, r, false)
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}
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return b.String()
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}
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const meta = `\.+*?()|[]{}^$# `
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func escape(b *bytes.Buffer, r rune, force bool) {
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if unicode.IsPrint(r) {
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if strings.IndexRune(meta, r) >= 0 || force {
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b.WriteRune('\\')
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}
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b.WriteRune(r)
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return
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}
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switch r {
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case '\a':
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b.WriteString(`\a`)
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case '\f':
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b.WriteString(`\f`)
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case '\n':
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b.WriteString(`\n`)
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case '\r':
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b.WriteString(`\r`)
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case '\t':
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b.WriteString(`\t`)
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case '\v':
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b.WriteString(`\v`)
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default:
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if r < 0x100 {
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b.WriteString(`\x`)
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s := strconv.FormatInt(int64(r), 16)
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if len(s) == 1 {
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b.WriteRune('0')
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}
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b.WriteString(s)
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break
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}
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b.WriteString(`\u`)
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b.WriteString(strconv.FormatInt(int64(r), 16))
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}
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}
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func Unescape(input string) (string, error) {
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idx := strings.IndexRune(input, '\\')
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// no slashes means no unescape needed
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if idx == -1 {
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return input, nil
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}
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buf := bytes.NewBufferString(input[:idx])
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// get the runes for the rest of the string -- we're going full parser scan on this
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p := parser{}
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p.setPattern(input[idx+1:])
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for {
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if p.rightMost() {
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return "", p.getErr(ErrIllegalEndEscape)
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}
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r, err := p.scanCharEscape()
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if err != nil {
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return "", err
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}
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buf.WriteRune(r)
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// are we done?
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if p.rightMost() {
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return buf.String(), nil
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}
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r = p.moveRightGetChar()
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for r != '\\' {
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buf.WriteRune(r)
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if p.rightMost() {
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// we're done, no more slashes
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return buf.String(), nil
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}
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// keep scanning until we get another slash
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r = p.moveRightGetChar()
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}
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}
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}
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