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Tokenizes strings that represent a regular expressions.
var ret = require('ret');
var tokens = ret(/foo|bar/.source);
tokens
will contain the following object
{
"type": ret.types.ROOT
"options": [
[ { "type": ret.types.CHAR, "value", 102 },
{ "type": ret.types.CHAR, "value", 111 },
{ "type": ret.types.CHAR, "value", 111 } ],
[ { "type": ret.types.CHAR, "value", 98 },
{ "type": ret.types.CHAR, "value", 97 },
{ "type": ret.types.CHAR, "value", 114 } ]
]
}
ret.types
is a collection of the various token types exported by ret.
Only used in the root of the regexp. This is needed due to the posibility of the root containing a pipe |
character. In that case, the token will have an options
key that will be an array of arrays of tokens. If not, it will contain a stack
key that is an array of tokens.
{
"type": ret.types.ROOT,
"stack": [token1, token2...],
}
{
"type": ret.types.ROOT,
"options" [
[token1, token2...],
[othertoken1, othertoken2...]
...
],
}
Groups contain tokens that are inside of a parenthesis. If the group begins with ?
followed by another character, it's a special type of group. A ':' tells the group not to be remembered when exec
is used. '=' means the previous token matches only if followed by this group, and '!' means the previous token matches only if NOT followed.
Like root, it can contain an options
key instead of stack
if there is a pipe.
{
"type": ret.types.GROUP,
"remember" true,
"followedBy": false,
"notFollowedBy": false,
"stack": [token1, token2...],
}
{
"type": ret.types.GROUP,
"remember" true,
"followedBy": false,
"notFollowedBy": false,
"options" [
[token1, token2...],
[othertoken1, othertoken2...]
...
],
}
\b
, \B
, ^
, and $
specify positions in the regexp.
{
"type": ret.types.POSITION,
"value": "^",
}
Contains a key set
specifying what tokens are allowed and a key not
specifying if the set should be negated. A set can contain other sets, ranges, and characters.
{
"type": ret.types.SET,
"set": [token1, token2...],
"not": false,
}
Used in set tokens to specify a character range. from
and to
are character codes.
{
"type": ret.types.RANGE,
"from": 97,
"to": 122,
}
{
"type": ret.types.REPETITION,
"min": 0,
"max": Infinity,
"value": token,
}
References a group token. value
is 1-9.
{
"type": ret.types.REFERENCE,
"value": 1,
}
Represents a single character token. value
is the character code. This might seem a bit cluttering instead of concatenating characters together. But since repetition tokens only repeat the last token and not the last clause like the pipe, it's simpler to do it this way.
{
"type": ret.types.CHAR,
"value": 123,
}
ret.js will throw errors if given a string with an invalid regular expression. All possible errors are
?
character is followed by an invalid character. It can only be followed by !
, =
, or :
. Example: /(?_abc)/
/foo|?bar/
, /{1,3}foo|bar/
, /foo(+bar)/
/hello)2u/
/(1(23)4/
/[abc/
npm install ret
Tests are written with vows
npm test
MIT