buffer-apg-js
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JavaScript APG, an ABNF Parser Generator
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<h1>Sticky Mode</h1>
<h3>Syntax</h3>
<pre>
var exp = new apgExp(pattern, "g");
</pre>
<p>
The pattern match attempt is made at the index, <kbd><a href="./lastIndex.html">exp.lastIndex</a></kbd>.
The user can set <kbd>exp.lastIndex</kbd> to any value prior to the match attempt.
If a match is not found <kbd>exp.lastIndex</kbd> the attempt fails and returns <kbd>null</kbd>.
In sticky mode if a match is found, <kbd>exp.lastIndex</kbd> is
incremented by the length of the matched pattern, or one if the length is zero.
(Some patterns allow matches to empty strings. In this case <kbd>exp.lastIndex</kbd>
is incremented by one to prevent infinite loops and to allow the sticky search to continue.)
This allows for an iteration over all <i>consecutive</i> matched patterns in the <kbd>input</kbd> string.
When the match fails, <kbd>exp.lastIndex</kbd> is then reset to zero.
</p>
<h3>Example 1</h3>
<pre>
var pattern, str, exp, result;
pattern = 'pattern = "abc"\n';
exp = new apgExp(pattern, "y");
str = "---abc---ABC---";
while(result = exp.exec(str)){
console.log("found: " + result[0] + " :at: " + result.index);
}
console.log("result: null");
/* returns */
result: null
</pre>
<h3>Example 2</h3>
<pre>
var pattern, str, exp, result;
pattern = 'pattern = "abc"\n';
exp = new apgExp(pattern, "y");
exp.lastIndex = 3;
str = "---abc---ABC---";
while(result = exp.exec(str)){
console.log("found: " + result[0] + " :at: " + result.index);
}
console.log("result: null");
/* returns */
found: abc :at: 3
result: null
</pre>
<h3>Example 3</h3>
<pre>
var pattern, str, exp, result;
pattern = 'pattern = "abc"\n';
exp = new apgExp(pattern, "y");
str = "abcABCabc";
while(result = exp.exec(str)){
console.log("found: " + result[0] + " :at: " + result.index);
}
console.log("result: null");
/* returns */
found: abc :at: 0
found: ABC :at: 3
found: abc :at: 6
result: null
</pre>
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