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
|
package parser
import (
"errors"
"fmt"
"log"
"reflect"
"strings"
"github.com/gnolang/parscan/lang"
)
// ParseType parses a list of tokens defining a type expresssion and returns
// the corresponding runtime type or an error.
func (p *Parser) ParseType(in Tokens) (typ reflect.Type, err error) {
log.Println("ParseType", in)
switch in[0].Id {
case lang.Func:
// Get argument and return token positions depending on function pattern:
// method with receiver, named function or anonymous closure.
// TODO: handle variadics
var out Tokens
var indexArgs int
switch l, in1 := len(in), in[1]; {
case l >= 4 && in1.Id == lang.ParenBlock && in[2].Id == lang.Ident:
indexArgs, out = 3, in[4:]
case l >= 3 && in1.Id == lang.Ident:
indexArgs, out = 2, in[3:]
case l >= 2 && in1.Id == lang.ParenBlock:
indexArgs, out = 1, in[2:]
default:
return nil, fmt.Errorf("invalid func signature")
}
// We can now parse function input and output parameter types.
// Input parameters are always enclosed by parenthesis.
iargs, err := p.Scan(in[indexArgs].Block(), false)
if err != nil {
return nil, err
}
arg, _, err := p.parseParamTypes(iargs, parseTypeIn)
if err != nil {
return nil, err
}
// Output parameters may be empty, or enclosed or not by parenthesis.
if len(out) == 1 && out[0].Id == lang.ParenBlock {
if out, err = p.Scan(out[0].Block(), false); err != nil {
return nil, err
}
}
ret, _, err := p.parseParamTypes(out, parseTypeOut)
if err != nil {
return nil, err
}
return reflect.FuncOf(arg, ret, false), nil
case lang.Ident:
// TODO: selector expression (pkg.type)
s, _, ok := p.getSym(in[0].Str, p.scope)
if !ok || s.kind != symType {
return nil, fmt.Errorf("invalid type %s", in[0].Str)
}
return s.Type, nil
}
return typ, err
}
type typeFlag int
const (
parseTypeIn typeFlag = iota
parseTypeOut
parseTypeVar
)
var missingTypeError = errors.New("Missing type")
// parseParamTypes parses a list of comma separated typed parameters and returns a list of
// runtime types. Implicit parameter names and types are supported.
func (p *Parser) parseParamTypes(in Tokens, flag typeFlag) (types []reflect.Type, vars []string, err error) {
// Parse from right to left, to allow multiple comma separated parameters of the same type.
list := in.Split(lang.Comma)
for i := len(list) - 1; i >= 0; i-- {
t := list[i]
if len(t) == 0 {
continue
}
param := ""
local := p.funcScope != ""
if p.hasFirstParam(t) {
param = strings.TrimPrefix(p.scope+"/"+t[0].Str, "/")
t = t[1:]
if len(t) == 0 {
if len(types) == 0 {
return nil, nil, missingTypeError
}
// Type was ommitted, apply the previous one from the right.
types = append([]reflect.Type{types[0]}, types...)
zv := reflect.New(types[0]).Elem().Interface()
switch flag {
case parseTypeIn:
p.addSym(-i-2, param, zv, symVar, types[0], true)
case parseTypeOut:
p.addSym(p.framelen[p.funcScope], param, zv, symVar, types[0], true)
p.framelen[p.funcScope]++
case parseTypeVar:
if local {
p.addSym(p.framelen[p.funcScope], param, zv, symVar, types[0], local)
p.framelen[p.funcScope]++
} else {
p.addSym(unsetAddr, param, zv, symVar, types[0], local)
}
}
vars = append(vars, param)
continue
}
}
typ, err := p.ParseType(t)
if err != nil {
return nil, nil, err
}
if param != "" {
zv := reflect.New(typ).Elem().Interface()
switch flag {
case parseTypeIn:
p.addSym(-i-2, param, zv, symVar, typ, true)
case parseTypeOut:
p.addSym(p.framelen[p.funcScope], param, zv, symVar, typ, true)
p.framelen[p.funcScope]++
case parseTypeVar:
if local {
p.addSym(p.framelen[p.funcScope], param, zv, symVar, typ, local)
p.framelen[p.funcScope]++
} else {
p.addSym(unsetAddr, param, zv, symVar, typ, local)
}
}
} else if flag == parseTypeOut {
p.framelen[p.funcScope]++
}
types = append([]reflect.Type{typ}, types...)
vars = append(vars, param)
}
return types, vars, err
}
// hasFirstParam returns true if the first token of a list is a parameter name.
func (p *Parser) hasFirstParam(in Tokens) bool {
if in[0].Id != lang.Ident {
return false
}
s, _, ok := p.getSym(in[0].Str, p.scope)
return !ok || s.kind != symType
}
|
