forked from cloudwan/gohan
/
lexer.go
249 lines (223 loc) · 4.51 KB
/
lexer.go
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// Copyright (C) 2016 Juniper Networks, 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 gohanscript
import (
"fmt"
"strconv"
"unicode/utf8"
"github.com/cloudwan/gohan/util"
)
//Additonal lexer code for support Ansible-like yaml notion.
const (
eof = -1
)
type lexer struct {
code []byte
position int
err error
}
func newLexer(src string) *lexer {
return &lexer{
position: 0,
code: []byte(src),
}
}
func isLetter(c rune) bool {
return 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || isDigit(c) || c == '_'
}
func isDigit(c rune) bool {
return '0' <= c && c <= '9'
}
func isWhiteSpace(c rune) bool {
return c == ' ' || c == '\t' || c == '\n'
}
func isNotWhiteSpace(c rune) bool {
return !(c == ' ' || c == '\t' || c == '\n' || c == eof)
}
func (l *lexer) next() rune {
if l.isEOF() {
return eof
}
c, width := utf8.DecodeRune(l.code[l.position:])
l.position += width
return c
}
func (l *lexer) peek() rune {
if l.isEOF() {
return eof
}
c, _ := utf8.DecodeRune(l.code[l.position:])
return c
}
func (l *lexer) isEOF() bool {
return l.position >= len(l.code) || l.err != nil
}
func (l *lexer) scanWhiteSpace() {
for isWhiteSpace(l.peek()) {
l.next()
}
}
func (l *lexer) error(error string) {
l.err = fmt.Errorf("Error %s at position %d", error, l.position)
}
func (l *lexer) clearError() {
l.err = nil
}
func (l *lexer) scanIdentifier() string {
var result []rune
firstChar := l.peek()
if !isLetter(firstChar) {
l.error("Identifier expected1")
}
for isLetter(l.peek()) {
result = append(result, l.next())
}
return string(result)
}
func (l *lexer) scanNumber() int {
var result int
firstChar := l.peek()
if !isDigit(firstChar) {
l.error("Digit expected")
}
for isDigit(l.peek()) {
c := l.next()
result = result*10 + (int(c) - '0')
}
return result
}
func (l *lexer) scanDoubleQuotedString() string {
var result []rune
firstChar := l.peek()
if firstChar != '"' {
l.error("value should be quoted")
return ""
}
l.next()
for {
c := l.peek()
switch c {
case '\\':
l.next()
result = append(result, l.next())
case '"':
l.next()
return string(result)
case eof:
l.error("string isn't terminated")
return ""
default:
result = append(result, l.next())
}
}
}
func (l *lexer) scanQuotedString() string {
var result []rune
firstChar := l.peek()
if firstChar != '\'' {
l.error("value should be quoted")
return ""
}
l.next()
for {
c := l.peek()
switch c {
case '\\':
l.next()
result = append(result, l.next())
case '\'':
l.next()
return string(result)
case eof:
l.error("string isn't terminated")
return ""
default:
result = append(result, l.next())
}
}
}
func (l *lexer) scanString() string {
var result []rune
for isNotWhiteSpace(l.peek()) {
result = append(result, l.next())
}
return string(result)
}
func (l *lexer) parseDict() map[string]interface{} {
result := map[string]interface{}{}
for {
l.scanWhiteSpace()
key := l.scanIdentifier()
var value interface{}
if l.err != nil {
return nil
}
l.scanWhiteSpace()
c := l.next()
if c != '=' {
l.error(" = expected")
return nil
}
l.scanWhiteSpace()
c = l.peek()
switch c {
case '\'':
value = l.scanQuotedString()
if l.err != nil {
return nil
}
case '"':
value = l.scanDoubleQuotedString()
if l.err != nil {
return nil
}
default:
s := l.scanString()
if l.err != nil {
return nil
}
i, err := strconv.Atoi(s)
if err == nil {
value = i
} else {
value = s
}
}
result[key] = value
l.scanWhiteSpace()
c = l.peek()
if c == eof {
return result
}
}
}
func parseCode(key string, code interface{}) map[string]interface{} {
switch c := code.(type) {
case string:
l := newLexer(c)
result := l.parseDict()
if l.err != nil {
args := map[string]interface{}{}
args[key] = c
return args
}
return result
case map[string]interface{}:
return c
case map[interface{}]interface{}:
return util.MaybeMap(c)
}
return map[string]interface{}{key: code}
}