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282 lines
6.4 KiB
282 lines
6.4 KiB
var util = require('./util');
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var types = require('./types');
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var sets = require('./sets');
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var positions = require('./positions');
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module.exports = function(regexpStr) {
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var i = 0, l, c,
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start = { type: types.ROOT, stack: []},
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// Keep track of last clause/group and stack.
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lastGroup = start,
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last = start.stack,
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groupStack = [];
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var repeatErr = function(i) {
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util.error(regexpStr, 'Nothing to repeat at column ' + (i - 1));
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};
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// Decode a few escaped characters.
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var str = util.strToChars(regexpStr);
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l = str.length;
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// Iterate through each character in string.
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while (i < l) {
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c = str[i++];
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switch (c) {
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// Handle escaped characters, inclues a few sets.
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case '\\':
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c = str[i++];
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switch (c) {
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case 'b':
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last.push(positions.wordBoundary());
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break;
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case 'B':
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last.push(positions.nonWordBoundary());
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break;
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case 'w':
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last.push(sets.words());
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break;
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case 'W':
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last.push(sets.notWords());
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break;
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case 'd':
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last.push(sets.ints());
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break;
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case 'D':
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last.push(sets.notInts());
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break;
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case 's':
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last.push(sets.whitespace());
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break;
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case 'S':
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last.push(sets.notWhitespace());
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break;
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default:
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// Check if c is integer.
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// In which case it's a reference.
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if (/\d/.test(c)) {
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last.push({ type: types.REFERENCE, value: parseInt(c, 10) });
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// Escaped character.
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} else {
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last.push({ type: types.CHAR, value: c.charCodeAt(0) });
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}
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}
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break;
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// Positionals.
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case '^':
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last.push(positions.begin());
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break;
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case '$':
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last.push(positions.end());
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break;
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// Handle custom sets.
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case '[':
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// Check if this class is 'anti' i.e. [^abc].
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var not;
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if (str[i] === '^') {
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not = true;
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i++;
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} else {
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not = false;
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}
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// Get all the characters in class.
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var classTokens = util.tokenizeClass(str.slice(i), regexpStr);
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// Increase index by length of class.
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i += classTokens[1];
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last.push({
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type: types.SET,
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set: classTokens[0],
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not: not,
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});
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break;
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// Class of any character except \n.
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case '.':
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last.push(sets.anyChar());
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break;
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// Push group onto stack.
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case '(':
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// Create group.
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var group = {
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type: types.GROUP,
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stack: [],
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remember: true,
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};
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c = str[i];
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// If if this is a special kind of group.
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if (c === '?') {
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c = str[i + 1];
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i += 2;
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// Match if followed by.
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if (c === '=') {
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group.followedBy = true;
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// Match if not followed by.
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} else if (c === '!') {
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group.notFollowedBy = true;
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} else if (c !== ':') {
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util.error(regexpStr,
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'Invalid group, character \'' + c +
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'\' after \'?\' at column ' + (i - 1));
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}
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group.remember = false;
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}
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// Insert subgroup into current group stack.
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last.push(group);
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// Remember the current group for when the group closes.
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groupStack.push(lastGroup);
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// Make this new group the current group.
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lastGroup = group;
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last = group.stack;
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break;
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// Pop group out of stack.
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case ')':
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if (groupStack.length === 0) {
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util.error(regexpStr, 'Unmatched ) at column ' + (i - 1));
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}
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lastGroup = groupStack.pop();
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// Check if this group has a PIPE.
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// To get back the correct last stack.
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last = lastGroup.options ?
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lastGroup.options[lastGroup.options.length - 1] : lastGroup.stack;
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break;
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// Use pipe character to give more choices.
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case '|':
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// Create array where options are if this is the first PIPE
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// in this clause.
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if (!lastGroup.options) {
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lastGroup.options = [lastGroup.stack];
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delete lastGroup.stack;
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}
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// Create a new stack and add to options for rest of clause.
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var stack = [];
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lastGroup.options.push(stack);
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last = stack;
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break;
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// Repetition.
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// For every repetition, remove last element from last stack
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// then insert back a RANGE object.
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// This design is chosen because there could be more than
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// one repetition symbols in a regex i.e. `a?+{2,3}`.
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case '{':
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var rs = /^(\d+)(,(\d+)?)?\}/.exec(str.slice(i)), min, max;
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if (rs !== null) {
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if (last.length === 0) {
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repeatErr(i);
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}
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min = parseInt(rs[1], 10);
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max = rs[2] ? rs[3] ? parseInt(rs[3], 10) : Infinity : min;
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i += rs[0].length;
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last.push({
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type: types.REPETITION,
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min: min,
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max: max,
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value: last.pop(),
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});
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} else {
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last.push({
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type: types.CHAR,
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value: 123,
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});
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}
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break;
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case '?':
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if (last.length === 0) {
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repeatErr(i);
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}
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last.push({
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type: types.REPETITION,
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min: 0,
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max: 1,
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value: last.pop(),
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});
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break;
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case '+':
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if (last.length === 0) {
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repeatErr(i);
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}
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last.push({
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type: types.REPETITION,
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min: 1,
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max: Infinity,
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value: last.pop(),
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});
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break;
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case '*':
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if (last.length === 0) {
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repeatErr(i);
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}
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last.push({
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type: types.REPETITION,
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min: 0,
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max: Infinity,
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value: last.pop(),
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});
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break;
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// Default is a character that is not `\[](){}?+*^$`.
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default:
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last.push({
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type: types.CHAR,
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value: c.charCodeAt(0),
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});
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}
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}
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// Check if any groups have not been closed.
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if (groupStack.length !== 0) {
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util.error(regexpStr, 'Unterminated group');
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}
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return start;
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};
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module.exports.types = types;
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