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parse.js
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Wed, Jan 22, 16:35

parse.js
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'use strict';
const stringify = require('./stringify');
/**
* Constants
*/
const {
MAX_LENGTH,
CHAR_BACKSLASH, /* \ */
CHAR_BACKTICK, /* ` */
CHAR_COMMA, /* , */
CHAR_DOT, /* . */
CHAR_LEFT_PARENTHESES, /* ( */
CHAR_RIGHT_PARENTHESES, /* ) */
CHAR_LEFT_CURLY_BRACE, /* { */
CHAR_RIGHT_CURLY_BRACE, /* } */
CHAR_LEFT_SQUARE_BRACKET, /* [ */
CHAR_RIGHT_SQUARE_BRACKET, /* ] */
CHAR_DOUBLE_QUOTE, /* " */
CHAR_SINGLE_QUOTE, /* ' */
CHAR_NO_BREAK_SPACE,
CHAR_ZERO_WIDTH_NOBREAK_SPACE
} = require('./constants');
/**
* parse
*/
const parse = (input, options = {}) => {
if (typeof input !== 'string') {
throw new TypeError('Expected a string');
}
let opts = options || {};
let max = typeof opts.maxLength === 'number' ? Math.min(MAX_LENGTH, opts.maxLength) : MAX_LENGTH;
if (input.length > max) {
throw new SyntaxError(`Input length (${input.length}), exceeds max characters (${max})`);
}
let ast = { type: 'root', input, nodes: [] };
let stack = [ast];
let block = ast;
let prev = ast;
let brackets = 0;
let length = input.length;
let index = 0;
let depth = 0;
let value;
let memo = {};
/**
* Helpers
*/
const advance = () => input[index++];
const push = node => {
if (node.type === 'text' && prev.type === 'dot') {
prev.type = 'text';
}
if (prev && prev.type === 'text' && node.type === 'text') {
prev.value += node.value;
return;
}
block.nodes.push(node);
node.parent = block;
node.prev = prev;
prev = node;
return node;
};
push({ type: 'bos' });
while (index < length) {
block = stack[stack.length - 1];
value = advance();
/**
* Invalid chars
*/
if (value === CHAR_ZERO_WIDTH_NOBREAK_SPACE || value === CHAR_NO_BREAK_SPACE) {
continue;
}
/**
* Escaped chars
*/
if (value === CHAR_BACKSLASH) {
push({ type: 'text', value: (options.keepEscaping ? value : '') + advance() });
continue;
}
/**
* Right square bracket (literal): ']'
*/
if (value === CHAR_RIGHT_SQUARE_BRACKET) {
push({ type: 'text', value: '\\' + value });
continue;
}
/**
* Left square bracket: '['
*/
if (value === CHAR_LEFT_SQUARE_BRACKET) {
brackets++;
let closed = true;
let next;
while (index < length && (next = advance())) {
value += next;
if (next === CHAR_LEFT_SQUARE_BRACKET) {
brackets++;
continue;
}
if (next === CHAR_BACKSLASH) {
value += advance();
continue;
}
if (next === CHAR_RIGHT_SQUARE_BRACKET) {
brackets--;
if (brackets === 0) {
break;
}
}
}
push({ type: 'text', value });
continue;
}
/**
* Parentheses
*/
if (value === CHAR_LEFT_PARENTHESES) {
block = push({ type: 'paren', nodes: [] });
stack.push(block);
push({ type: 'text', value });
continue;
}
if (value === CHAR_RIGHT_PARENTHESES) {
if (block.type !== 'paren') {
push({ type: 'text', value });
continue;
}
block = stack.pop();
push({ type: 'text', value });
block = stack[stack.length - 1];
continue;
}
/**
* Quotes: '|"|`
*/
if (value === CHAR_DOUBLE_QUOTE || value === CHAR_SINGLE_QUOTE || value === CHAR_BACKTICK) {
let open = value;
let next;
if (options.keepQuotes !== true) {
value = '';
}
while (index < length && (next = advance())) {
if (next === CHAR_BACKSLASH) {
value += next + advance();
continue;
}
if (next === open) {
if (options.keepQuotes === true) value += next;
break;
}
value += next;
}
push({ type: 'text', value });
continue;
}
/**
* Left curly brace: '{'
*/
if (value === CHAR_LEFT_CURLY_BRACE) {
depth++;
let dollar = prev.value && prev.value.slice(-1) === '$' || block.dollar === true;
let brace = {
type: 'brace',
open: true,
close: false,
dollar,
depth,
commas: 0,
ranges: 0,
nodes: []
};
block = push(brace);
stack.push(block);
push({ type: 'open', value });
continue;
}
/**
* Right curly brace: '}'
*/
if (value === CHAR_RIGHT_CURLY_BRACE) {
if (block.type !== 'brace') {
push({ type: 'text', value });
continue;
}
let type = 'close';
block = stack.pop();
block.close = true;
push({ type, value });
depth--;
block = stack[stack.length - 1];
continue;
}
/**
* Comma: ','
*/
if (value === CHAR_COMMA && depth > 0) {
if (block.ranges > 0) {
block.ranges = 0;
let open = block.nodes.shift();
block.nodes = [open, { type: 'text', value: stringify(block) }];
}
push({ type: 'comma', value });
block.commas++;
continue;
}
/**
* Dot: '.'
*/
if (value === CHAR_DOT && depth > 0 && block.commas === 0) {
let siblings = block.nodes;
if (depth === 0 || siblings.length === 0) {
push({ type: 'text', value });
continue;
}
if (prev.type === 'dot') {
block.range = [];
prev.value += value;
prev.type = 'range';
if (block.nodes.length !== 3 && block.nodes.length !== 5) {
block.invalid = true;
block.ranges = 0;
prev.type = 'text';
continue;
}
block.ranges++;
block.args = [];
continue;
}
if (prev.type === 'range') {
siblings.pop();
let before = siblings[siblings.length - 1];
before.value += prev.value + value;
prev = before;
block.ranges--;
continue;
}
push({ type: 'dot', value });
continue;
}
/**
* Text
*/
push({ type: 'text', value });
}
// Mark imbalanced braces and brackets as invalid
do {
block = stack.pop();
if (block.type !== 'root') {
block.nodes.forEach(node => {
if (!node.nodes) {
if (node.type === 'open') node.isOpen = true;
if (node.type === 'close') node.isClose = true;
if (!node.nodes) node.type = 'text';
node.invalid = true;
}
});
// get the location of the block on parent.nodes (block's siblings)
let parent = stack[stack.length - 1];
let index = parent.nodes.indexOf(block);
// replace the (invalid) block with it's nodes
parent.nodes.splice(index, 1, ...block.nodes);
}
} while (stack.length > 0);
push({ type: 'eos' });
return ast;
};
module.exports = parse;

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