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Support exponent notation, trailing . for ints and other parsing details.

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Sami Samhuri 2009-12-09 23:17:57 -08:00
parent 19ac65cb2b
commit 22856cc925
1 changed files with 47 additions and 8 deletions
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55
el/parser.js
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@ -6,9 +6,6 @@
// Released under the terms of the MIT license. See the included file
// LICENSE.
/****************************************************************
**** Parser ****************************************************
****************************************************************/
EL.Parser = function(data) {
this.data = data || '';
@ -148,23 +145,65 @@ EL.Parser.prototype.parseRegex = function() {
}, true /* consume terminator */));
};
// In Emacs Lisp a trailing . is allowed on integers.
// Valid kinds of numbers we parse here are:
//
// * Integers of the form 42, +17, -300, 7300. (trailing .), +1. and
// -1.
//
// * Floating point numbers of the form -4.5, 0.0, and +933825.3450133492
//
// * Exponential notation for floats, e.g. 1.5e2 (150.0) or 420e-1 (42.0)
// (There is no trailing . allowed anywhere in exponent notation)
EL.Parser.prototype.parseNumber = function() {
var sign = this.peek() == '-' ? this.consumeChar() : '+',
var value = this.parseIntOrFloat(),
exponentAllowed = value === parseInt(value),
exp;
// now check for an exponent
if (this.exponentAllowed && (this.peek() == 'e' || this.peek() == 'E')) {
this.consumeChar();
// Technically this is an error as a float is not allowed for exponents
// but the regex is strict enough to keep us from trying to do that.
exp = this.parseIntOrFloat();
value *= Math.pow(10, exp);
}
return value;
};
// Pack int and float parsing together for simplicity's sake.
EL.Parser.prototype.parseIntOrFloat = function() {
this.exponentAllowed = true;
var sign = this.peek() == '-' || this.peek() == '+' ? this.consumeChar() : '+',
value = this.parseUntil(/[^\d]/, 0, function(n,c) {
return n*10 + parseInt(c);
});
// if we see a . there might be a float to parse
if (this.peek() == '.') {
this.exponentAllowed = false;
this.consumeChar();
var decimal = this.parseUntil(/[^\d]/, '', function(s,c) {return s + c;});
value = parseFloat('' + value + '.' + decimal);
if (this.peek() && this.peek().match(/\d/)) {
var decimal = this.parseUntil(/[^\d]/, '', function(s,c) {return s + c;});
value = parseFloat('' + value + '.' + decimal);
}
}
return sign == '-' ? -1*value : value;
return sign == '-' ? -1*value : value;
};
// These regexes matches all the inputs specified above parseNumber.
EL.Parser.prototype.lookingAtNumber = function() {
var pos = this.pos,
rest = this.rest(),
match = rest.match(/^(-)?\d+(\.\d+)?[\s)\n]/) || rest.match(/^(-)?\d+(\.\d+)?$/);
match = rest.match(/^[+-]?\d+(\.\d*)?[)\s\n]/)
|| rest.match(/^[+-]?\d+(\.\d*)?$/)
|| rest.match(/^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?[)\s\n]/)
|| rest.match(/^[+-]?\d+(\.\d+)?([eE][+-]?\d+)?$/);
return (match != null);
};