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
|
package parsec
import (
"bytes"
"fmt"
)
func Nil(p Pointer) (Node, Pointer) {
return nil, p
}
func Never(p Pointer) (Node, Pointer) {
return Error{p.pos, "Never matches"}, p
}
func And(parsers ...Parserish) Parser {
if len(parsers) == 0 {
return Nil
}
ps := ParsifyAll(parsers...)
return func(p Pointer) (Node, Pointer) {
var nodes = make([]Node, 0, len(ps))
var node Node
newP := p
for _, parser := range ps {
node, newP = parser(newP)
if node == nil {
continue
}
if IsError(node) {
return node, p
}
nodes = append(nodes, node)
}
return nodes, newP
}
}
func Any(parsers ...Parserish) Parser {
if len(parsers) == 0 {
return Nil
}
ps := ParsifyAll(parsers...)
return func(p Pointer) (Node, Pointer) {
errors := []Error{}
for _, parser := range ps {
node, newP := parser(p)
if err, isErr := node.(Error); isErr {
errors = append(errors, err)
continue
}
return node, newP
}
longestError := errors[0]
for _, e := range errors[1:] {
if e.pos > longestError.pos {
longestError = e
}
}
return longestError, p
}
}
func Kleene(opScan Parserish, sepScan ...Parserish) Parser {
return manyImpl(0, opScan, Never, sepScan...)
}
func KleeneUntil(opScan Parserish, untilScan Parserish, sepScan ...Parserish) Parser {
return manyImpl(0, opScan, untilScan, sepScan...)
}
func Many(opScan Parserish, sepScan ...Parserish) Parser {
return manyImpl(1, opScan, Never, sepScan...)
}
func ManyUntil(opScan Parserish, untilScan Parserish, sepScan ...Parserish) Parser {
return manyImpl(1, opScan, untilScan, sepScan...)
}
func manyImpl(min int, op Parserish, until Parserish, sep ...Parserish) Parser {
opParser := Parsify(op)
untilParser := Parsify(until)
sepParser := Nil
if len(sep) > 0 {
sepParser = Parsify(sep[0])
}
return func(p Pointer) (Node, Pointer) {
var node Node
nodes := make([]Node, 0)
newP := p
for {
if node, _ := untilParser(newP); !IsError(node) {
if len(nodes) < min {
return NewError(newP.pos, "Unexpected input"), p
}
break
}
if node, newP = opParser(newP); IsError(node) {
if len(nodes) < min {
return node, p
}
break
}
nodes = append(nodes, node)
if node, newP = sepParser(newP); IsError(node) {
break
}
}
return nodes, newP
}
}
func Maybe(parser Parserish) Parser {
realParser := Parsify(parser)
return func(p Pointer) (Node, Pointer) {
node, newP := realParser(p)
if IsError(node) {
return nil, p
}
return node, newP
}
}
func Map(parser Parserish, f func(n Node) Node) Parser {
p := Parsify(parser)
return func(ptr Pointer) (Node, Pointer) {
node, newPtr := p(ptr)
if IsError(node) {
return node, ptr
}
return f(node), newPtr
}
}
func flatten(n Node) string {
if s, ok := n.(string); ok {
return s
}
if nodes, ok := n.([]Node); ok {
sbuf := &bytes.Buffer{}
for _, node := range nodes {
sbuf.WriteString(flatten(node))
}
return sbuf.String()
}
panic(fmt.Errorf("Dont know how to flatten %t", n))
}
func Merge(parser Parserish) Parser {
return Map(parser, func(n Node) Node {
return flatten(n)
})
}
|
