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Nasal: new function string.compileTemplate

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This allows to create functions to build string based on
templates used for examample with most common tilemap
engines.
This commit is contained in:
Thomas Geymayer 2014-01-30 11:23:14 +01:00
parent 1c1bcda8d6
commit cab89b1b5a
1 changed files with 43 additions and 0 deletions
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43
Nasal/string.nas
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@ -241,6 +241,49 @@ replace = func(str, old, new) {
})(); # end tamper-proof environment
##
# Get a function out of a string template for fast insertion of template
# parameters. This allows to use the same templates as with most available tile
# mapping engines (eg. Leaflet, Polymaps). Return a callable function object on
# success, and nil if parsing the templated fails.
#
# Example (Build MapQuest tile url):
#
# var makeUrl = string.compileTemplate(
# "http://otile1.mqcdn.com/tiles/1.0.0/map/{z}/{x}/{y}.jpg"
# );
# print( makeUrl({x: 5, y: 4, z: 3}) );
#
# Output:
#
# http://otile1.mqcdn.com/tiles/1.0.0/map/3/5/4.jpg
#
var compileTemplate = func(template)
{
# See http://james.padolsey.com/javascript/straight-up-interpolation/
var code = '';
var start = 0;
var end = 0;
while( (start = template.find('{', end)) >= 0 )
{
if( end > 0 )
code ~= '~';
code ~= '"' ~ substr(template, end, start - end) ~ '"';
if( (end = template.find('}', start)) < 0 )
{
debug.warn("string.compileTemplate: unclosed '{' (" ~ template ~ ")");
return nil;
}
code ~= '~arg[0]["' ~ substr(template, start + 1, end - start - 1) ~ '"]';
end += 1;
}
if( end >= 0 )
code ~= '~"' ~ substr(template, end, size(template) - end) ~ '"';
code ~= ';';
return compile(code);
}
##