98 lines
2.1 KiB
JavaScript
98 lines
2.1 KiB
JavaScript
/**
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* The MIT License (MIT)
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* Copyright (c) 2017-present Dmitry Soshnikov <[email protected]>
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*/
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'use strict';
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/**
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* A regexp-tree plugin to replace single char character classes with
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* just that character.
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*
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* [\d] -> \d, [^\w] -> \W
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*/
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module.exports = {
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CharacterClass: function CharacterClass(path) {
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var node = path.node;
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if (node.expressions.length !== 1 || !hasAppropriateSiblings(path) || !isAppropriateChar(node.expressions[0])) {
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return;
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}
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var _node$expressions$ = node.expressions[0],
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value = _node$expressions$.value,
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kind = _node$expressions$.kind,
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escaped = _node$expressions$.escaped;
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if (node.negative) {
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// For negative can extract only meta chars like [^\w] -> \W
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// cannot do for [^a] -> a (wrong).
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if (!isMeta(value)) {
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return;
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}
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value = getInverseMeta(value);
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}
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path.replace({
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type: 'Char',
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value: value,
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kind: kind,
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escaped: escaped || shouldEscape(value)
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});
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}
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};
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function isAppropriateChar(node) {
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return node.type === 'Char' &&
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// We don't extract [\b] (backspace) since \b has different
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// semantics (word boundary).
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node.value !== '\\b';
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}
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function isMeta(value) {
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return (/^\\[dwsDWS]$/.test(value)
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);
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}
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function getInverseMeta(value) {
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return (/[dws]/.test(value) ? value.toUpperCase() : value.toLowerCase()
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);
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}
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function hasAppropriateSiblings(path) {
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var parent = path.parent,
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index = path.index;
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if (parent.type !== 'Alternative') {
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return true;
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}
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var previousNode = parent.expressions[index - 1];
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if (previousNode == null) {
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return true;
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}
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// Don't optimized \1[0] to \10
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if (previousNode.type === 'Backreference' && previousNode.kind === 'number') {
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return false;
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}
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// Don't optimized \2[0] to \20
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if (previousNode.type === 'Char' && previousNode.kind === 'decimal') {
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return false;
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}
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return true;
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}
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// Note: \{ and \} are always preserved to avoid `a[{]2[}]` turning
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// into `a{2}`.
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function shouldEscape(value) {
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return (/[*[()+?$./{}|]/.test(value)
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);
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} |