forked from projectcalico/libcalico-go
-
Notifications
You must be signed in to change notification settings - Fork 0
/
parser.go
230 lines (216 loc) · 6.13 KB
/
parser.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
// Copyright (c) 2016 Tigera, Inc. All rights reserved.
// 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 (
"errors"
"fmt"
log "github.com/Sirupsen/logrus"
"github.com/projectcalico/libcalico-go/lib/selector/tokenizer"
)
const parserDebug = false
// Parse a string representation of a selector expression into a Selector.
func Parse(selector string) (sel Selector, err error) {
log.Debugf("Parsing %#v", selector)
tokens, err := tokenizer.Tokenize(selector)
if err != nil {
return
}
if tokens[0].Kind == tokenizer.TokEof {
return selectorRoot{root: AllNode{}}, nil
}
log.Debugf("Tokens %v", tokens)
// The "||" operator has the lowest precedence so we start with that.
node, remTokens, err := parseOrExpression(tokens)
if err != nil {
return
}
if len(remTokens) != 1 {
err = errors.New(fmt.Sprint("unexpected content at end of selector ", remTokens))
return
}
sel = selectorRoot{root: node}
return
}
// parseOrExpression parses a one or more "&&" terms, separated by "||" operators.
func parseOrExpression(tokens []tokenizer.Token) (sel node, remTokens []tokenizer.Token, err error) {
if parserDebug {
log.Debugf("Parsing ||s from %v", tokens)
}
// Look for the first expression.
andNodes := make([]node, 0)
sel, remTokens, err = parseAndExpression(tokens)
if err != nil {
return
}
andNodes = append(andNodes, sel)
// Then loop looking for "||" followed by an <expression>
for {
switch remTokens[0].Kind {
case tokenizer.TokOr:
remTokens = remTokens[1:]
sel, remTokens, err = parseAndExpression(remTokens)
if err != nil {
return
}
andNodes = append(andNodes, sel)
default:
if len(andNodes) == 1 {
sel = andNodes[0]
} else {
sel = OrNode{andNodes}
}
return
}
}
}
// parseAndExpression parses a one or more operations, separated by "&&" operators.
func parseAndExpression(tokens []tokenizer.Token) (sel node, remTokens []tokenizer.Token, err error) {
if parserDebug {
log.Debugf("Parsing &&s from %v", tokens)
}
// Look for the first operation.
opNodes := make([]node, 0)
sel, remTokens, err = parseOperation(tokens)
if err != nil {
return
}
opNodes = append(opNodes, sel)
// Then loop looking for "&&" followed by another operation.
for {
switch remTokens[0].Kind {
case tokenizer.TokAnd:
remTokens = remTokens[1:]
sel, remTokens, err = parseOperation(remTokens)
if err != nil {
return
}
opNodes = append(opNodes, sel)
default:
if len(opNodes) == 1 {
sel = opNodes[0]
} else {
sel = AndNode{opNodes}
}
return
}
}
}
// parseOperations parses a single, possibly negated operation (i.e. ==, !=, has()).
// It also handles calling parseOrExpression recursively for parenthesized expressions.
func parseOperation(tokens []tokenizer.Token) (sel node, remTokens []tokenizer.Token, err error) {
if parserDebug {
log.Debugf("Parsing op from %v", tokens)
}
if len(tokens) == 0 {
err = errors.New("Unexpected end of string looking for op")
return
}
// First, collapse any leading "!" operators to a single boolean.
negated := false
for {
if tokens[0].Kind == tokenizer.TokNot {
negated = !negated
tokens = tokens[1:]
} else {
break
}
}
// Then, look for the various types of operator.
switch tokens[0].Kind {
case tokenizer.TokHas:
sel = HasNode{tokens[0].Value.(string)}
remTokens = tokens[1:]
case tokenizer.TokAll:
sel = AllNode{}
remTokens = tokens[1:]
case tokenizer.TokLabel:
// should have an operator and a literal.
if len(tokens) < 3 {
err = errors.New(fmt.Sprint("Unexpected end of string in middle of op", tokens))
return
}
switch tokens[1].Kind {
case tokenizer.TokEq:
if tokens[2].Kind == tokenizer.TokStringLiteral {
sel = LabelEqValueNode{tokens[0].Value.(string), tokens[2].Value.(string)}
remTokens = tokens[3:]
} else {
err = errors.New("Expected string")
}
case tokenizer.TokNe:
if tokens[2].Kind == tokenizer.TokStringLiteral {
sel = LabelNeValueNode{tokens[0].Value.(string), tokens[2].Value.(string)}
remTokens = tokens[3:]
} else {
err = errors.New("Expected string")
}
case tokenizer.TokIn, tokenizer.TokNotIn:
if tokens[2].Kind == tokenizer.TokLBrace {
remTokens = tokens[3:]
values := []string{}
for {
if remTokens[0].Kind == tokenizer.TokStringLiteral {
value := remTokens[0].Value.(string)
values = append(values, value)
remTokens = remTokens[1:]
if remTokens[0].Kind == tokenizer.TokComma {
remTokens = remTokens[1:]
} else {
break
}
} else {
break
}
}
if remTokens[0].Kind != tokenizer.TokRBrace {
err = errors.New("Expected }")
} else {
// Skip over the }
remTokens = remTokens[1:]
labelName := tokens[0].Value.(string)
set := ConvertToStringSetInPlace(values) // Mutates values.
if tokens[1].Kind == tokenizer.TokIn {
sel = LabelInSetNode{labelName, set}
} else {
sel = LabelNotInSetNode{labelName, set}
}
}
} else {
err = errors.New("Expected set literal")
}
default:
err = errors.New(fmt.Sprint("Expected == or != not ", tokens[1]))
return
}
case tokenizer.TokLParen:
// We hit a paren, skip past it, then recurse.
sel, remTokens, err = parseOrExpression(tokens[1:])
if err != nil {
return
}
// After parsing the nested expression, there should be
// a matching paren.
if len(remTokens) < 1 || remTokens[0].Kind != tokenizer.TokRParen {
err = errors.New("Expected )")
return
}
remTokens = remTokens[1:]
default:
err = errors.New(fmt.Sprint("Unexpected token: ", tokens[0]))
return
}
if negated && err == nil {
sel = NotNode{sel}
}
return
}