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
|
package pongo2
/* Incomplete:
-----------
verbatim (only the "name" argument is missing for verbatim)
Reconsideration:
----------------
debug (reason: not sure what to output yet)
regroup / Grouping on other properties (reason: maybe too python-specific; not sure how useful this would be in Go)
Following built-in tags wont be added:
--------------------------------------
csrf_token (reason: web-framework specific)
load (reason: python-specific)
url (reason: web-framework specific)
*/
import (
"fmt"
)
type INodeTag interface {
INode
}
// This is the function signature of the tag's parser you will have
// to implement in order to create a new tag.
//
// 'doc' is providing access to the whole document while 'arguments'
// is providing access to the user's arguments to the tag:
//
// {% your_tag_name some "arguments" 123 %}
//
// start_token will be the *Token with the tag's name in it (here: your_tag_name).
//
// Please see the Parser documentation on how to use the parser.
// See RegisterTag()'s documentation for more information about
// writing a tag as well.
type TagParser func(doc *Parser, start *Token, arguments *Parser) (INodeTag, *Error)
type tag struct {
name string
parser TagParser
}
var tags map[string]*tag
func init() {
tags = make(map[string]*tag)
}
// Registers a new tag. You usually want to call this
// function in the tag's init() function:
// http://golang.org/doc/effective_go.html#init
//
// See http://www.florian-schlachter.de/post/pongo2/ for more about
// writing filters and tags.
func RegisterTag(name string, parserFn TagParser) error {
_, existing := tags[name]
if existing {
return fmt.Errorf("tag with name '%s' is already registered", name)
}
tags[name] = &tag{
name: name,
parser: parserFn,
}
return nil
}
// Replaces an already registered tag with a new implementation. Use this
// function with caution since it allows you to change existing tag behaviour.
func ReplaceTag(name string, parserFn TagParser) error {
_, existing := tags[name]
if !existing {
return fmt.Errorf("tag with name '%s' does not exist (therefore cannot be overridden)", name)
}
tags[name] = &tag{
name: name,
parser: parserFn,
}
return nil
}
// Tag = "{%" IDENT ARGS "%}"
func (p *Parser) parseTagElement() (INodeTag, *Error) {
p.Consume() // consume "{%"
tokenName := p.MatchType(TokenIdentifier)
// Check for identifier
if tokenName == nil {
return nil, p.Error("Tag name must be an identifier.", nil)
}
// Check for the existing tag
tag, exists := tags[tokenName.Val]
if !exists {
// Does not exists
return nil, p.Error(fmt.Sprintf("Tag '%s' not found (or beginning tag not provided)", tokenName.Val), tokenName)
}
// Check sandbox tag restriction
if _, isBanned := p.template.set.bannedTags[tokenName.Val]; isBanned {
return nil, p.Error(fmt.Sprintf("Usage of tag '%s' is not allowed (sandbox restriction active).", tokenName.Val), tokenName)
}
var argsToken []*Token
for p.Peek(TokenSymbol, "%}") == nil && p.Remaining() > 0 {
// Add token to args
argsToken = append(argsToken, p.Current())
p.Consume() // next token
}
// EOF?
if p.Remaining() == 0 {
return nil, p.Error("Unexpectedly reached EOF, no tag end found.", p.lastToken)
}
p.Match(TokenSymbol, "%}")
argParser := newParser(p.name, argsToken, p.template)
if len(argsToken) == 0 {
// This is done to have nice EOF error messages
argParser.lastToken = tokenName
}
p.template.level++
defer func() { p.template.level-- }()
return tag.parser(p, tokenName, argParser)
}
|
