102 lines
3 KiB
JavaScript
102 lines
3 KiB
JavaScript
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import { expand, select, cache } from "./nodes";
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import { VALUE_INDEX, KEY_INDEX, PARENT_INDEX, POINTER_INDEX } from "./keys";
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function collect(func, input, node, pointer) {
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const result = [];
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for (let i = 0, l = input.length; i < l; i += 1) {
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result.push(...func(node, input[i], node, pointer));
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}
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return result;
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}
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function reduce(func, input, node, pointer) {
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const result = [];
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for (let i = 0, l = input.length; i < l; i += 1) {
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const output = func(node, input[i], pointer);
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if (output) {
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result.push(output);
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}
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}
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return result;
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}
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function query(data, ast, pointer) {
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let result = data;
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ast.children.forEach((node) => {
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if (expand[node.type]) {
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result = collect(expand[node.type], result, node, pointer);
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}
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else if (select[node.type]) {
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result = reduce(select[node.type], result, node, pointer);
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}
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else {
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throw new Error(`Unknown filter ${node.type}`);
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}
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});
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return result;
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}
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function runPatternOnce(inputSet, ast, pointer) {
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const resultingSet = [];
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let workingSet = inputSet;
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ast.children.forEach((node) => {
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if (node.type === "orPattern") {
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resultingSet.push(...workingSet);
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workingSet = inputSet;
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return;
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}
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workingSet = runNode(workingSet, node, pointer);
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});
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resultingSet.push(...workingSet);
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return resultingSet;
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}
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function getIterationCount(quantifier) {
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if (quantifier == null) {
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return 1; // default, simple group
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}
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if (quantifier === "*" || quantifier === "+") {
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return Infinity;
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}
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const count = parseInt(quantifier);
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return isNaN(count) ? 1 : count;
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}
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function pattern(data, ast, pointer) {
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const result = [];
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const quantifier = ast.children.find((node) => node.type === "quantifier");
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const iterationCount = getIterationCount(quantifier && quantifier.text);
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let workingSet = data;
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if (quantifier && quantifier.text === "*") {
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result.push(...workingSet);
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}
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let count = 0;
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while (workingSet.length > 0 && count < iterationCount) {
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workingSet = runPatternOnce(workingSet, ast, pointer);
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result.push(...workingSet);
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count += 1;
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}
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return result;
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}
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function skip(data, ast, pointer) {
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let result = data;
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ast.children.forEach((n) => (result = runNode(result, n, pointer)));
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return result;
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}
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function runNode(data, ast, pointer) {
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let result;
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if (ast.type === "query") {
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result = query(data, ast, pointer);
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}
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else if (ast.type === "pattern") {
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result = pattern(data, ast, pointer);
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}
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else {
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result = skip(data, ast, pointer);
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}
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// after each query or pattern, reset the cache, to (re)enable nested queries
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cache.reset();
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cache.mem.push(data);
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return result;
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}
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export function run(data, ast) {
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cache.reset();
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cache.mem.push(data);
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return runNode([[data, null, null, "#"]], ast);
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}
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export { VALUE_INDEX, KEY_INDEX, PARENT_INDEX, POINTER_INDEX };
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