ret
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Tokenizes a string that represents a regular expression.
361 lines • 14.7 kB
JavaScript
;
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if (k2 === undefined) k2 = k;
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var __importStar = (this && this.__importStar) || function (mod) {
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var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.tokenizer = void 0;
const util = __importStar(require("./util"));
const types_1 = require("./types");
const sets = __importStar(require("./sets"));
/**
* Valid opening characters for capture group names.
*/
const captureGroupFirstChar = /^[a-zA-Z_$]$/i;
/**
* Valid characters for capture group names.
*/
const captureGroupChars = /^[a-zA-Z0-9_$]$/i;
const digit = /\d/;
/**
* Tokenizes a regular expression (that is currently a string)
* @param {string} regexpStr String of regular expression to be tokenized
*
* @returns {Root}
*/
exports.tokenizer = (regexpStr) => {
let i = 0, c;
let start = { type: types_1.types.ROOT, stack: [] };
// Keep track of last clause/group and stack.
let lastGroup = start;
let last = start.stack;
let groupStack = [];
let referenceQueue = [];
let groupCount = 0;
const repeatErr = (col) => {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Nothing to repeat at column ${col - 1}`);
};
// Decode a few escaped characters.
let str = util.strToChars(regexpStr);
// Iterate through each character in string.
while (i < str.length) {
switch (c = str[i++]) {
// Handle escaped characters, inclues a few sets.
case '\\':
if (i === str.length) {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: \\ at end of pattern`);
}
switch (c = str[i++]) {
case 'b':
last.push({ type: types_1.types.POSITION, value: 'b' });
break;
case 'B':
last.push({ type: types_1.types.POSITION, value: 'B' });
break;
case 'w':
last.push(sets.words());
break;
case 'W':
last.push(sets.notWords());
break;
case 'd':
last.push(sets.ints());
break;
case 'D':
last.push(sets.notInts());
break;
case 's':
last.push(sets.whitespace());
break;
case 'S':
last.push(sets.notWhitespace());
break;
default:
// Check if c is integer.
// In which case it's a reference.
if (digit.test(c)) {
let digits = c;
while (i < str.length && digit.test(str[i])) {
digits += str[i++];
}
let value = parseInt(digits, 10);
const reference = { type: types_1.types.REFERENCE, value };
last.push(reference);
referenceQueue.push({ reference, stack: last, index: last.length - 1 });
// Escaped character.
}
else {
last.push({ type: types_1.types.CHAR, value: c.charCodeAt(0) });
}
}
break;
// Positionals.
case '^':
last.push({ type: types_1.types.POSITION, value: '^' });
break;
case '$':
last.push({ type: types_1.types.POSITION, value: '$' });
break;
// Handle custom sets.
case '[': {
// Check if this class is 'anti' i.e. [^abc].
let not;
if (str[i] === '^') {
not = true;
i++;
}
else {
not = false;
}
// Get all the characters in class.
let classTokens = util.tokenizeClass(str.slice(i), regexpStr);
// Increase index by length of class.
i += classTokens[1];
last.push({
type: types_1.types.SET,
set: classTokens[0],
not,
});
break;
}
// Class of any character except \n.
case '.':
last.push(sets.anyChar());
break;
// Push group onto stack.
case '(': {
// Create group.
let group = {
type: types_1.types.GROUP,
stack: [],
remember: true,
};
// If this is a special kind of group.
if (str[i] === '?') {
c = str[i + 1];
i += 2;
// Match if followed by.
if (c === '=') {
group.followedBy = true;
group.remember = false;
// Match if not followed by.
}
else if (c === '!') {
group.notFollowedBy = true;
group.remember = false;
}
else if (c === '<') {
let name = '';
if (captureGroupFirstChar.test(str[i])) {
name += str[i];
i++;
}
else {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Invalid capture group name, character '${str[i]}'` +
` after '<' at column ${i + 1}`);
}
while (i < str.length && captureGroupChars.test(str[i])) {
name += str[i];
i++;
}
if (!name) {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Invalid capture group name, character '${str[i]}'` +
` after '<' at column ${i + 1}`);
}
if (str[i] !== '>') {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Unclosed capture group name, expected '>', found` +
` '${str[i]}' at column ${i + 1}`);
}
group.name = name;
i++;
}
else if (c === ':') {
group.remember = false;
}
else {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Invalid group, character '${c}'` +
` after '?' at column ${i - 1}`);
}
}
else {
groupCount += 1;
}
// Insert subgroup into current group stack.
last.push(group);
// Remember the current group for when the group closes.
groupStack.push(lastGroup);
// Make this new group the current group.
lastGroup = group;
last = group.stack;
break;
}
// Pop group out of stack.
case ')':
if (groupStack.length === 0) {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Unmatched ) at column ${i - 1}`);
}
lastGroup = groupStack.pop();
// Check if this group has a PIPE.
// To get back the correct last stack.
last = lastGroup.options ?
lastGroup.options[lastGroup.options.length - 1] :
lastGroup.stack;
break;
// Use pipe character to give more choices.
case '|': {
// Create array where options are if this is the first PIPE
// in this clause.
if (!lastGroup.options) {
lastGroup.options = [lastGroup.stack];
delete lastGroup.stack;
}
// Create a new stack and add to options for rest of clause.
let stack = [];
lastGroup.options.push(stack);
last = stack;
break;
}
// Repetition.
// For every repetition, remove last element from last stack
// then insert back a RANGE object.
// This design is chosen because there could be more than
// one repetition symbols in a regex i.e. `a?+{2,3}`.
case '{': {
let rs = /^(\d+)(,(\d+)?)?\}/.exec(str.slice(i)), min, max;
if (rs !== null) {
if (last.length === 0) {
repeatErr(i);
}
min = parseInt(rs[1], 10);
max = rs[2] ? rs[3] ? parseInt(rs[3], 10) : Infinity : min;
i += rs[0].length;
last.push({
type: types_1.types.REPETITION,
min,
max,
value: last.pop(),
});
}
else {
last.push({
type: types_1.types.CHAR,
value: 123,
});
}
break;
}
case '?':
if (last.length === 0) {
repeatErr(i);
}
last.push({
type: types_1.types.REPETITION,
min: 0,
max: 1,
value: last.pop(),
});
break;
case '+':
if (last.length === 0) {
repeatErr(i);
}
last.push({
type: types_1.types.REPETITION,
min: 1,
max: Infinity,
value: last.pop(),
});
break;
case '*':
if (last.length === 0) {
repeatErr(i);
}
last.push({
type: types_1.types.REPETITION,
min: 0,
max: Infinity,
value: last.pop(),
});
break;
// Default is a character that is not `\[](){}?+*^$`.
default:
last.push({
type: types_1.types.CHAR,
value: c.charCodeAt(0),
});
}
}
// Check if any groups have not been closed.
if (groupStack.length !== 0) {
throw new SyntaxError(`Invalid regular expression: /${regexpStr}/: Unterminated group`);
}
updateReferences(referenceQueue, groupCount);
return start;
};
/**
* This is a side effecting function that changes references to chars
* if there are not enough capturing groups to reference
* See: https://github.com/fent/ret.js/pull/39#issuecomment-1006475703
* See: https://github.com/fent/ret.js/issues/38
* @param {(Reference | Char)[]} referenceQueue
* @param {number} groupCount
* @returns {void}
*/
function updateReferences(referenceQueue, groupCount) {
// Note: We go through the queue in reverse order so
// that index we use is correct even if we have to add
// multiple tokens to one stack
for (const elem of referenceQueue.reverse()) {
if (groupCount < elem.reference.value) {
// If there is nothing to reference then turn this into a char token
elem.reference.type = types_1.types.CHAR;
const valueString = elem.reference.value.toString();
elem.reference.value = parseInt(valueString, 8);
// If the number is not octal then we need to create multiple tokens
// https://github.com/fent/ret.js/pull/39#issuecomment-1008229226
if (!/^[0-7]+$/.test(valueString)) {
let i = 0;
while (valueString[i] !== '8' && valueString[i] !== '9') {
i += 1;
}
if (i === 0) {
// Handling case when escaped number starts with 8 or 9
elem.reference.value = valueString.charCodeAt(0);
i += 1;
}
else {
// If the escaped number does not start with 8 or 9, then all
// 0-7 digits before the first 8/9 form the first character code
// see: https://github.com/fent/ret.js/pull/39#discussion_r780747085
elem.reference.value = parseInt(valueString.slice(0, i), 8);
}
if (valueString.length > i) {
const tail = elem.stack.splice(elem.index + 1);
for (const char of valueString.slice(i)) {
elem.stack.push({
type: types_1.types.CHAR,
value: char.charCodeAt(0),
});
}
elem.stack.push(...tail);
}
}
}
}
}
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