112 lines
3.1 KiB
JavaScript
112 lines
3.1 KiB
JavaScript
/**
|
|
* @license Apache-2.0
|
|
*
|
|
* Copyright (c) 2022 The Stdlib Authors.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
// MODULES //
|
|
|
|
var isNumber = require( './is_number.js' );
|
|
|
|
// NOTE: for the following, we explicitly avoid using stdlib packages in this particular package in order to avoid circular dependencies.
|
|
var abs = Math.abs; // eslint-disable-line stdlib/no-builtin-math
|
|
var lowercase = String.prototype.toLowerCase;
|
|
var uppercase = String.prototype.toUpperCase;
|
|
var replace = String.prototype.replace;
|
|
|
|
|
|
// VARIABLES //
|
|
|
|
var RE_EXP_POS_DIGITS = /e\+(\d)$/;
|
|
var RE_EXP_NEG_DIGITS = /e-(\d)$/;
|
|
var RE_ONLY_DIGITS = /^(\d+)$/;
|
|
var RE_DIGITS_BEFORE_EXP = /^(\d+)e/;
|
|
var RE_TRAILING_PERIOD_ZERO = /\.0$/;
|
|
var RE_PERIOD_ZERO_EXP = /\.0*e/;
|
|
var RE_ZERO_BEFORE_EXP = /(\..*[^0])0*e/;
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Formats a token object argument as a floating-point number.
|
|
*
|
|
* @private
|
|
* @param {Object} token - token object
|
|
* @throws {Error} must provide a valid floating-point number
|
|
* @returns {string} formatted token argument
|
|
*/
|
|
function formatDouble( token ) {
|
|
var digits;
|
|
var out;
|
|
var f = parseFloat( token.arg );
|
|
if ( !isFinite( f ) ) { // NOTE: We use the global `isFinite` function here instead of `@stdlib/math/base/assert/is-finite` in order to avoid circular dependencies.
|
|
if ( !isNumber( token.arg ) ) {
|
|
throw new Error( 'invalid floating-point number. Value: ' + out );
|
|
}
|
|
// Case: NaN, Infinity, or -Infinity
|
|
f = token.arg;
|
|
}
|
|
switch ( token.specifier ) {
|
|
case 'e':
|
|
case 'E':
|
|
out = f.toExponential( token.precision );
|
|
break;
|
|
case 'f':
|
|
case 'F':
|
|
out = f.toFixed( token.precision );
|
|
break;
|
|
case 'g':
|
|
case 'G':
|
|
if ( abs( f ) < 0.0001 ) {
|
|
digits = token.precision;
|
|
if ( digits > 0 ) {
|
|
digits -= 1;
|
|
}
|
|
out = f.toExponential( digits );
|
|
} else {
|
|
out = f.toPrecision( token.precision );
|
|
}
|
|
if ( !token.alternate ) {
|
|
out = replace.call( out, RE_ZERO_BEFORE_EXP, '$1e' );
|
|
out = replace.call( out, RE_PERIOD_ZERO_EXP, 'e');
|
|
out = replace.call( out, RE_TRAILING_PERIOD_ZERO, '' );
|
|
}
|
|
break;
|
|
default:
|
|
throw new Error( 'invalid double notation. Value: ' + token.specifier );
|
|
}
|
|
out = replace.call( out, RE_EXP_POS_DIGITS, 'e+0$1' );
|
|
out = replace.call( out, RE_EXP_NEG_DIGITS, 'e-0$1' );
|
|
if ( token.alternate ) {
|
|
out = replace.call( out, RE_ONLY_DIGITS, '$1.' );
|
|
out = replace.call( out, RE_DIGITS_BEFORE_EXP, '$1.e' );
|
|
}
|
|
if ( f >= 0 && token.sign ) {
|
|
out = token.sign + out;
|
|
}
|
|
out = ( token.specifier === uppercase.call( token.specifier ) ) ?
|
|
uppercase.call( out ) :
|
|
lowercase.call( out );
|
|
return out;
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = formatDouble;
|