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
|
{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, CPP #-}
{-
Copyright (C) 2009-2010 John MacFarlane <jgm@berkeley.edu>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-}
{- |
Module : Text.Pandoc.Templates
Copyright : Copyright (C) 2009-2010 John MacFarlane
License : GNU GPL, version 2 or above
Maintainer : John MacFarlane <jgm@berkeley.edu>
Stability : alpha
Portability : portable
A simple templating system with variable substitution and conditionals.
Example:
> renderTemplate [("name","Sam"),("salary","50,000")] $
> "Hi, $name$. $if(salary)$You make $$$salary$.$else$No salary data.$endif$"
> "Hi, John. You make $50,000."
A slot for an interpolated variable is a variable name surrounded
by dollar signs. To include a literal @$@ in your template, use
@$$@. Variable names must begin with a letter and can contain letters,
numbers, @_@, and @-@.
The value of a variable will be indented to the same level as the
variable.
A conditional begins with @$if(variable_name)$@ and ends with @$endif$@.
It may optionally contain an @$else$@ section. The if section is
used if @variable_name@ has a non-null value, otherwise the else section
is used.
Conditional keywords should not be indented, or unexpected spacing
problems may occur.
If a variable name is associated with multiple values in the association
list passed to 'renderTemplate', you may use the @$for$@ keyword to
iterate over them:
> renderTemplate [("name","Sam"),("name","Joe")] $
> "$for(name)$\nHi, $name$.\n$endfor$"
> "Hi, Sam.\nHi, Joe."
You may optionally specify separators using @$sep$@:
> renderTemplate [("name","Sam"),("name","Joe"),("name","Lynn")] $
> "Hi, $for(name)$$name$$sep$, $endfor$"
> "Hi, Sam, Joe, Lynn."
-}
module Text.Pandoc.Templates ( renderTemplate
, TemplateTarget
, getDefaultTemplate ) where
import Text.Parsec
import Control.Monad (liftM, when, forM, mzero)
import System.FilePath
import Data.List (intercalate, intersperse)
#if MIN_VERSION_blaze_html(0,5,0)
import Text.Blaze.Html (Html)
import Text.Blaze.Internal (preEscapedString)
#else
import Text.Blaze (preEscapedString, Html)
#endif
import Data.ByteString.Lazy.UTF8 (ByteString, fromString)
import Text.Pandoc.Shared (readDataFile)
import qualified Control.Exception.Extensible as E (try, IOException)
-- | Get default template for the specified writer.
getDefaultTemplate :: (Maybe FilePath) -- ^ User data directory to search first
-> String -- ^ Name of writer
-> IO (Either E.IOException String)
getDefaultTemplate user writer = do
let format = takeWhile (`notElem` "+-") writer -- strip off extensions
case format of
"native" -> return $ Right ""
"json" -> return $ Right ""
"docx" -> return $ Right ""
"epub" -> return $ Right ""
"odt" -> getDefaultTemplate user "opendocument"
"markdown_strict" -> getDefaultTemplate user "markdown"
"multimarkdown" -> getDefaultTemplate user "markdown"
"markdown_github" -> getDefaultTemplate user "markdown"
_ -> let fname = "templates" </> "default" <.> format
in E.try $ readDataFile user fname
data TemplateState = TemplateState Int [(String,String)]
adjustPosition :: String -> Parsec [Char] TemplateState String
adjustPosition str = do
let lastline = takeWhile (/= '\n') $ reverse str
updateState $ \(TemplateState pos x) ->
if str == lastline
then TemplateState (pos + length lastline) x
else TemplateState (length lastline) x
return str
class TemplateTarget a where
toTarget :: String -> a
instance TemplateTarget String where
toTarget = id
instance TemplateTarget ByteString where
toTarget = fromString
instance TemplateTarget Html where
toTarget = preEscapedString
-- | Renders a template
renderTemplate :: TemplateTarget a
=> [(String,String)] -- ^ Assoc. list of values for variables
-> String -- ^ Template
-> a
renderTemplate vals templ =
case runParser (do x <- parseTemplate; eof; return x) (TemplateState 0 vals) "template" templ of
Left e -> error $ show e
Right r -> toTarget $ concat r
reservedWords :: [String]
reservedWords = ["else","endif","for","endfor","sep"]
parseTemplate :: Parsec [Char] TemplateState [String]
parseTemplate =
many $ (plaintext <|> escapedDollar <|> conditional <|> for <|> variable)
>>= adjustPosition
plaintext :: Parsec [Char] TemplateState String
plaintext = many1 $ noneOf "$"
escapedDollar :: Parsec [Char] TemplateState String
escapedDollar = try $ string "$$" >> return "$"
skipEndline :: Parsec [Char] st ()
skipEndline = try $ skipMany (oneOf " \t") >> newline >> return ()
conditional :: Parsec [Char] TemplateState String
conditional = try $ do
TemplateState pos vars <- getState
string "$if("
id' <- ident
string ")$"
-- if newline after the "if", then a newline after "endif" will be swallowed
multiline <- option False $ try $ skipEndline >> return True
ifContents <- liftM concat parseTemplate
-- reset state for else block
setState $ TemplateState pos vars
elseContents <- option "" $ do try (string "$else$")
when multiline $ optional skipEndline
liftM concat parseTemplate
string "$endif$"
when multiline $ optional skipEndline
let conditionSatisfied = case lookup id' vars of
Nothing -> False
Just "" -> False
Just _ -> True
return $ if conditionSatisfied
then ifContents
else elseContents
for :: Parsec [Char] TemplateState String
for = try $ do
TemplateState pos vars <- getState
string "$for("
id' <- ident
string ")$"
-- if newline after the "for", then a newline after "endfor" will be swallowed
multiline <- option False $ try $ skipEndline >> return True
let matches = filter (\(k,_) -> k == id') vars
let indent = replicate pos ' '
contents <- forM matches $ \m -> do
updateState $ \(TemplateState p v) -> TemplateState p (m:v)
raw <- liftM concat $ lookAhead parseTemplate
return $ intercalate ('\n':indent) $ lines $ raw ++ "\n"
parseTemplate
sep <- option "" $ do try (string "$sep$")
when multiline $ optional skipEndline
liftM concat parseTemplate
string "$endfor$"
when multiline $ optional skipEndline
setState $ TemplateState pos vars
return $ concat $ intersperse sep contents
ident :: Parsec [Char] TemplateState String
ident = do
first <- letter
rest <- many (alphaNum <|> oneOf "_-")
let id' = first : rest
if id' `elem` reservedWords
then mzero
else return id'
variable :: Parsec [Char] TemplateState String
variable = try $ do
char '$'
id' <- ident
char '$'
TemplateState pos vars <- getState
let indent = replicate pos ' '
return $ case lookup id' vars of
Just val -> intercalate ('\n' : indent) $ lines val
Nothing -> ""
|
