var parse = require('../definition-syntax/parse');
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var MATCH = { type: 'Match' };
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var MISMATCH = { type: 'Mismatch' };
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var DISALLOW_EMPTY = { type: 'DisallowEmpty' };
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var LEFTPARENTHESIS = 40; // (
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var RIGHTPARENTHESIS = 41; // )
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function createCondition(match, thenBranch, elseBranch) {
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// reduce node count
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if (thenBranch === MATCH && elseBranch === MISMATCH) {
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return match;
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}
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if (match === MATCH && thenBranch === MATCH && elseBranch === MATCH) {
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return match;
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}
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if (match.type === 'If' && match.else === MISMATCH && thenBranch === MATCH) {
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thenBranch = match.then;
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match = match.match;
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}
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return {
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type: 'If',
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match: match,
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then: thenBranch,
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else: elseBranch
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};
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}
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function isFunctionType(name) {
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return (
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name.length > 2 &&
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name.charCodeAt(name.length - 2) === LEFTPARENTHESIS &&
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name.charCodeAt(name.length - 1) === RIGHTPARENTHESIS
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);
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}
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function isEnumCapatible(term) {
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return (
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term.type === 'Keyword' ||
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term.type === 'AtKeyword' ||
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term.type === 'Function' ||
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term.type === 'Type' && isFunctionType(term.name)
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);
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}
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function buildGroupMatchGraph(combinator, terms, atLeastOneTermMatched) {
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switch (combinator) {
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case ' ':
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// Juxtaposing components means that all of them must occur, in the given order.
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//
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// a b c
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// =
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// match a
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// then match b
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// then match c
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// then MATCH
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// else MISMATCH
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// else MISMATCH
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// else MISMATCH
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var result = MATCH;
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for (var i = terms.length - 1; i >= 0; i--) {
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var term = terms[i];
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result = createCondition(
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term,
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result,
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MISMATCH
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);
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};
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return result;
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case '|':
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// A bar (|) separates two or more alternatives: exactly one of them must occur.
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//
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// a | b | c
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// =
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// match a
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// then MATCH
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// else match b
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// then MATCH
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// else match c
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// then MATCH
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// else MISMATCH
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var result = MISMATCH;
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var map = null;
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for (var i = terms.length - 1; i >= 0; i--) {
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var term = terms[i];
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// reduce sequence of keywords into a Enum
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if (isEnumCapatible(term)) {
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if (map === null && i > 0 && isEnumCapatible(terms[i - 1])) {
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map = Object.create(null);
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result = createCondition(
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{
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type: 'Enum',
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map: map
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},
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MATCH,
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result
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);
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}
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if (map !== null) {
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var key = (isFunctionType(term.name) ? term.name.slice(0, -1) : term.name).toLowerCase();
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if (key in map === false) {
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map[key] = term;
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continue;
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}
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}
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}
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map = null;
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// create a new conditonal node
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result = createCondition(
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term,
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MATCH,
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result
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);
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};
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return result;
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case '&&':
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// A double ampersand (&&) separates two or more components,
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// all of which must occur, in any order.
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// Use MatchOnce for groups with a large number of terms,
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// since &&-groups produces at least N!-node trees
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if (terms.length > 5) {
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return {
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type: 'MatchOnce',
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terms: terms,
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all: true
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};
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}
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// Use a combination tree for groups with small number of terms
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//
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// a && b && c
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// =
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// match a
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// then [b && c]
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// else match b
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// then [a && c]
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// else match c
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// then [a && b]
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// else MISMATCH
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//
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// a && b
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// =
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// match a
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// then match b
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// then MATCH
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// else MISMATCH
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// else match b
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// then match a
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// then MATCH
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// else MISMATCH
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// else MISMATCH
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var result = MISMATCH;
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for (var i = terms.length - 1; i >= 0; i--) {
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var term = terms[i];
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var thenClause;
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if (terms.length > 1) {
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thenClause = buildGroupMatchGraph(
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combinator,
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terms.filter(function(newGroupTerm) {
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return newGroupTerm !== term;
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}),
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false
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);
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} else {
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thenClause = MATCH;
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}
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result = createCondition(
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term,
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thenClause,
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result
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);
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};
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return result;
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case '||':
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// A double bar (||) separates two or more options:
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// one or more of them must occur, in any order.
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// Use MatchOnce for groups with a large number of terms,
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// since ||-groups produces at least N!-node trees
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if (terms.length > 5) {
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return {
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type: 'MatchOnce',
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terms: terms,
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all: false
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};
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}
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// Use a combination tree for groups with small number of terms
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//
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// a || b || c
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// =
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// match a
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// then [b || c]
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// else match b
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// then [a || c]
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// else match c
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// then [a || b]
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// else MISMATCH
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//
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// a || b
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// =
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// match a
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// then match b
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// then MATCH
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// else MATCH
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// else match b
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// then match a
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// then MATCH
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// else MATCH
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// else MISMATCH
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var result = atLeastOneTermMatched ? MATCH : MISMATCH;
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for (var i = terms.length - 1; i >= 0; i--) {
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var term = terms[i];
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var thenClause;
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if (terms.length > 1) {
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thenClause = buildGroupMatchGraph(
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combinator,
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terms.filter(function(newGroupTerm) {
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return newGroupTerm !== term;
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}),
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true
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);
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} else {
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thenClause = MATCH;
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}
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result = createCondition(
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term,
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thenClause,
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result
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);
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};
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return result;
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}
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}
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function buildMultiplierMatchGraph(node) {
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var result = MATCH;
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var matchTerm = buildMatchGraph(node.term);
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if (node.max === 0) {
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// disable repeating of empty match to prevent infinite loop
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matchTerm = createCondition(
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matchTerm,
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DISALLOW_EMPTY,
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MISMATCH
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);
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// an occurrence count is not limited, make a cycle;
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// to collect more terms on each following matching mismatch
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result = createCondition(
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matchTerm,
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null, // will be a loop
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MISMATCH
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);
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result.then = createCondition(
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MATCH,
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MATCH,
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result // make a loop
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);
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if (node.comma) {
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result.then.else = createCondition(
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{ type: 'Comma', syntax: node },
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result,
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MISMATCH
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);
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}
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} else {
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// create a match node chain for [min .. max] interval with optional matches
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for (var i = node.min || 1; i <= node.max; i++) {
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if (node.comma && result !== MATCH) {
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result = createCondition(
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{ type: 'Comma', syntax: node },
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result,
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MISMATCH
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);
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}
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result = createCondition(
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matchTerm,
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createCondition(
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MATCH,
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MATCH,
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result
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),
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MISMATCH
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);
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}
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}
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if (node.min === 0) {
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// allow zero match
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result = createCondition(
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MATCH,
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MATCH,
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result
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);
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} else {
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// create a match node chain to collect [0 ... min - 1] required matches
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for (var i = 0; i < node.min - 1; i++) {
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if (node.comma && result !== MATCH) {
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result = createCondition(
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{ type: 'Comma', syntax: node },
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result,
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MISMATCH
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);
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}
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result = createCondition(
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matchTerm,
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result,
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MISMATCH
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);
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}
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}
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return result;
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}
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function buildMatchGraph(node) {
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if (typeof node === 'function') {
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return {
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type: 'Generic',
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fn: node
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};
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}
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switch (node.type) {
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case 'Group':
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var result = buildGroupMatchGraph(
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node.combinator,
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node.terms.map(buildMatchGraph),
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false
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);
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if (node.disallowEmpty) {
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result = createCondition(
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result,
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DISALLOW_EMPTY,
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MISMATCH
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);
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}
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return result;
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case 'Multiplier':
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return buildMultiplierMatchGraph(node);
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case 'Type':
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case 'Property':
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return {
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type: node.type,
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name: node.name,
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syntax: node
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};
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case 'Keyword':
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return {
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type: node.type,
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name: node.name.toLowerCase(),
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syntax: node
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};
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|
case 'AtKeyword':
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return {
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type: node.type,
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name: '@' + node.name.toLowerCase(),
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syntax: node
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};
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|
case 'Function':
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return {
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type: node.type,
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name: node.name.toLowerCase() + '(',
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syntax: node
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};
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|
case 'String':
|
// convert a one char length String to a Token
|
if (node.value.length === 3) {
|
return {
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type: 'Token',
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value: node.value.charAt(1),
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syntax: node
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};
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}
|
|
// otherwise use it as is
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return {
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type: node.type,
|
value: node.value.substr(1, node.value.length - 2).replace(/\\'/g, '\''),
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syntax: node
|
};
|
|
case 'Token':
|
return {
|
type: node.type,
|
value: node.value,
|
syntax: node
|
};
|
|
case 'Comma':
|
return {
|
type: node.type,
|
syntax: node
|
};
|
|
default:
|
throw new Error('Unknown node type:', node.type);
|
}
|
}
|
|
module.exports = {
|
MATCH: MATCH,
|
MISMATCH: MISMATCH,
|
DISALLOW_EMPTY: DISALLOW_EMPTY,
|
buildMatchGraph: function(syntaxTree, ref) {
|
if (typeof syntaxTree === 'string') {
|
syntaxTree = parse(syntaxTree);
|
}
|
|
return {
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type: 'MatchGraph',
|
match: buildMatchGraph(syntaxTree),
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syntax: ref || null,
|
source: syntaxTree
|
};
|
}
|
};
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