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/*
* Copyright (C) 2016 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
"use strict";
// Loosely based on ECMA 55 sections 4-8, but loosened to allow for modern conventions, like
// multi-character variable names. But this doesn't go too far - in particular, this doesn't do
// unicode, because that would require more thought.
function* lex(string)
{
let sourceLineNumber = 0;
for (let line of string.split("\n")) {
++sourceLineNumber;
function consumeWhitespace()
{
if (/^\s+/.test(line))
line = RegExp.rightContext;
}
function consume(kind)
{
line = RegExp.rightContext;
return {kind, string: RegExp.lastMatch, sourceLineNumber, userLineNumber};
}
const isIdentifier = /^[a-z_]([a-z0-9_]*)/i;
const isNumber = /^(([0-9]+(\.([0-9]*))?)|(\.[0-9]+)(e([+-]?)([0-9]+))?)/i;
const isString = /^\"([^\"]|(\"\"))*\"/;
const isKeyword = /^((base)|(data)|(def)|(dim)|(end)|(for)|(go)|(gosub)|(goto)|(if)|(input)|(let)|(next)|(on)|(option)|(print)|(randomize)|(read)|(restore)|(return)|(step)|(stop)|(sub)|(then)|(to))/i;
const isOperator = /^(-|\+|\*|\/|\^|\(|\)|(<[>=]?)|(>=?)|=|,|\$|;)/;
const isRem = /^rem\s.*/;
consumeWhitespace();
if (!/^[0-9]+/.test(line))
throw new Error("At line " + sourceLineNumber + ": Expect line number: " + line);
let userLineNumber = +RegExp.lastMatch;
line = RegExp.rightContext;
yield {kind: "userLineNumber", string: RegExp.lastMatch, sourceLineNumber, userLineNumber};
consumeWhitespace();
while (line.length) {
if (isKeyword.test(line))
yield consume("keyword");
else if (isIdentifier.test(line))
yield consume("identifier");
else if (isNumber.test(line)) {
let token = consume("number");
token.value = +token.string;
yield token;
} else if (isString.test(line)) {
let token = consume("string");
token.value = "";
for (let i = 1; i < token.string.length - 1; ++i) {
let char = token.string.charAt(i);
if (char == "\"")
i++;
token.value += char;
}
yield token;
} else if (isOperator.test(line))
yield consume("operator");
else if (isRem.test(line))
yield consume("remark");
else
throw new Error("At line " + sourceLineNumber + ": Cannot lex token: " + line);
consumeWhitespace();
}
// Note: this is necessary for the parser, which may look-ahead without checking if we're
// done. Fortunately, it won't look-ahead past a newLine.
yield {kind: "newLine", string:"\n", sourceLineNumber, userLineNumber};
}
}
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