/
contextfn.go
152 lines (111 loc) · 3.4 KB
/
contextfn.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
package exec
import (
"fmt"
"strings"
"github.com/ChrisTrenkamp/xsel/grammar"
"github.com/ChrisTrenkamp/xsel/grammar/parser/bsr"
"github.com/ChrisTrenkamp/xsel/grammar/parser/symbols"
)
type contextFn func(context *exprContext, expr *grammar.Grammar) error
var contextFunctions = map[symbols.NT]contextFn{}
func init() {
contextFunctions[symbols.NT_Literal] = execLiteral
contextFunctions[symbols.NT_UnionExprUnion] = execUnionExprUnion
contextFunctions[symbols.NT_FunctionCall] = execFunctionCall
contextFunctions[symbols.NT_VariableReference] = execVariableReference
}
func execLiteral(context *exprContext, expr *grammar.Grammar) error {
literal := expr.GetString()
literal = literal[1 : len(literal)-1]
context.result = String(literal)
return nil
}
func execUnionExprUnion(context *exprContext, expr *grammar.Grammar) error {
left, right, err := leftRightIndependentResult(context, expr)
if err != nil {
return err
}
leftNodeSet, lok := left.(NodeSet)
rightNodeSet, rok := right.(NodeSet)
if !lok || !rok {
return fmt.Errorf("cannot union non-NodeSet's")
}
context.result = unionCleanup(append(leftNodeSet, rightNodeSet...))
return nil
}
func unionCleanup(nextResult NodeSet) NodeSet {
// Technically, the XPath 1.0 specification leaves the order of a
// union operator undefined, but I think it's reasonable to return
// the result in document order.
return unique(cleanupForwardAxis(nextResult))
}
func execFunctionCall(context *exprContext, expr *grammar.Grammar) error {
children := make([]*bsr.BSR, 0, 2)
for _, cn := range expr.BSR.GetAllNTChildren() {
for _, c := range cn {
children = append(children, &c)
}
}
bsrs := make([]*bsr.BSR, 0)
gatherFunctionArgs(children[1], &bsrs)
args := make([]Result, 0, len(bsrs))
for _, i := range bsrs {
nextContext := context.copy()
nextExpr := expr.Next(i)
if err := execContext(&nextContext, nextExpr); err != nil {
return err
}
args = append(args, nextContext.result)
}
qname, err := GetQName(expr.Next(children[0]).GetString(), context.NamespaceDecls)
if err != nil {
return err
}
fn := context.FunctionLibrary[qname]
if fn == nil {
fn = context.builtinFunctions[qname]
}
if fn == nil {
return fmt.Errorf("could not find function %s", qname)
}
result, err := fn(context, args...)
if err != nil {
return fmt.Errorf("error invoking function %s: %s", qname, err)
}
context.result = result
return nil
}
func gatherFunctionArgs(b *bsr.BSR, args *[]*bsr.BSR) {
children := make([]*bsr.BSR, 0, 2)
for _, cn := range b.GetAllNTChildren() {
for _, c := range cn {
children = append(children, &c)
}
}
name := b.Label.Slot().NT
if (name == symbols.NT_FunctionSignature || name == symbols.NT_FunctionCallArgumentList) && len(children) == 1 {
gatherFunctionArgs(children[0], args)
return
}
if len(children) >= 1 {
*args = append(*args, children[0])
}
if len(children) == 2 {
gatherFunctionArgs(children[1], args)
}
}
func execVariableReference(context *exprContext, expr *grammar.Grammar) error {
variableStr := expr.Next(expr.BSR).GetString()
variableStr = strings.TrimSpace(variableStr)
variableStr = strings.TrimPrefix(variableStr, "$")
qname, err := GetQName(variableStr, context.NamespaceDecls)
if err != nil {
return err
}
variable := context.Variables[qname]
if variable == nil {
return fmt.Errorf("could not find variable %s", qname)
}
context.result = variable
return nil
}