Last Match Properties

After a successful pattern-matching attempt, the apgExp object retains information about the last-matched patterns or phrases. Unlike the result object which retains all matched phrases for all rule names, the apgExp object retains only the last matched.

Syntax

var exp    = new apgExp(pattern[, flags]);
var result = exe.exec(input);    

Last Match Properties

• exe.input (alias exe["$_"]): A copy of the input string^†.
• exe.lastMatch (alias exe["$&"]): A copy of the last-matched pattern - same as result[0]
• exe.leftContext (alias exe["$`"]): Prefix of the input string up to the first character of the matched pattern.
• exe.rightContext (alias exe["$'"]): Suffix of the input string, the phrase following the matched pattern.
• exe.rules (alias exe["${rule-name}"]): The last-matched phrase for the named rule.

^† If Unicode mode is true, i.e. flags = "u", all strings are arrays of integer character codes, otherwise it is a JavaScript string.

See Also

• exe.toText()
• exe.toHtml()
• exe.toHtmlPage()

Example

var pattern, exp, str, result;
pattern  = 'word  = alpha *(alpha / num)\n';
pattern += 'alpha = %d65-90 / %d97-122\n';
pattern += 'num   = %d48-57\n';
exp = new apgExp(pattern);
str = "---ab12...";
result = exp.exec(str);
console.log("exp.leftContext : "+exp.leftContext);
console.log('exp["$`"]       : '+exp["$`"]);
console.log("exp.lastMatch   : "+exp.lastMatch);
console.log('exp["$&"]       : '+exp["$&"]);
console.log("exp.rightContext: "+exp.rightContext);
console.log('exp["$\'"]       : '+exp["$'"]);
console.log("exp.rules.word  : "+exp.rules.word);
console.log("exp[${word}]    : "+exp["${word}"]);
console.log("exp.rules.alpha : "+exp.rules.alpha);
console.log("exp[${alpha}]   : "+exp["${alpha}"]);
console.log("exp.rules.num   : "+exp.rules.num);
console.log("exp[${num}]     : "+exp["${num}"]);
/* result */
exp.leftContext : ---
exp["$`"]       : ---
exp.lastMatch   : ab12
exp["$&"]       : ab12
exp.rightContext: ...
exp["$'"]       : ...
exp.rules.word  : ab12
exp[${word}]    : ab12
exp.rules.alpha : b
exp[${alpha}]   : b
exp.rules.num   : 2
exp[${num}]     : 2