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699 lines
18 KiB
JavaScript
699 lines
18 KiB
JavaScript
"use strict";
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const asts = require( "../asts" );
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const js = require( "../js" );
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const op = require( "../opcodes" );
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const visitor = require( "../visitor" );
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// Generates bytecode.
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//
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// Instructions
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// ============
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//
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// Stack Manipulation
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// ------------------
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//
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// [0] PUSH c
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//
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// stack.push(consts[c]);
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//
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// [1] PUSH_UNDEFINED
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//
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// stack.push(undefined);
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//
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// [2] PUSH_NULL
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//
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// stack.push(null);
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//
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// [3] PUSH_FAILED
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//
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// stack.push(FAILED);
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//
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// [4] PUSH_EMPTY_ARRAY
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//
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// stack.push([]);
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//
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// [5] PUSH_CURR_POS
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//
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// stack.push(currPos);
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//
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// [6] POP
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//
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// stack.pop();
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//
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// [7] POP_CURR_POS
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//
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// currPos = stack.pop();
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//
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// [8] POP_N n
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//
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// stack.pop(n);
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//
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// [9] NIP
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//
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// value = stack.pop();
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// stack.pop();
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// stack.push(value);
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//
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// [10] APPEND
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//
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// value = stack.pop();
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// array = stack.pop();
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// array.push(value);
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// stack.push(array);
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//
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// [11] WRAP n
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//
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// stack.push(stack.pop(n));
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//
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// [12] TEXT
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//
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// stack.push(input.substring(stack.pop(), currPos));
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//
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// Conditions and Loops
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// --------------------
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//
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// [13] IF t, f
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//
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// if (stack.top()) {
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// interpret(ip + 3, ip + 3 + t);
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// } else {
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// interpret(ip + 3 + t, ip + 3 + t + f);
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// }
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//
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// [14] IF_ERROR t, f
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//
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// if (stack.top() === FAILED) {
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// interpret(ip + 3, ip + 3 + t);
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// } else {
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// interpret(ip + 3 + t, ip + 3 + t + f);
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// }
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//
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// [15] IF_NOT_ERROR t, f
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//
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// if (stack.top() !== FAILED) {
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// interpret(ip + 3, ip + 3 + t);
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// } else {
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// interpret(ip + 3 + t, ip + 3 + t + f);
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// }
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//
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// [16] WHILE_NOT_ERROR b
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//
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// while(stack.top() !== FAILED) {
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// interpret(ip + 2, ip + 2 + b);
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// }
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//
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// Matching
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// --------
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//
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// [17] MATCH_ANY a, f, ...
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//
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// if (input.length > currPos) {
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// interpret(ip + 3, ip + 3 + a);
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// } else {
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// interpret(ip + 3 + a, ip + 3 + a + f);
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// }
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//
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// [18] MATCH_STRING s, a, f, ...
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//
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// if (input.substr(currPos, consts[s].length) === consts[s]) {
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// interpret(ip + 4, ip + 4 + a);
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// } else {
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// interpret(ip + 4 + a, ip + 4 + a + f);
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// }
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//
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// [19] MATCH_STRING_IC s, a, f, ...
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//
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// if (input.substr(currPos, consts[s].length).toLowerCase() === consts[s]) {
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// interpret(ip + 4, ip + 4 + a);
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// } else {
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// interpret(ip + 4 + a, ip + 4 + a + f);
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// }
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//
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// [20] MATCH_REGEXP r, a, f, ...
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//
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// if (consts[r].test(input.charAt(currPos))) {
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// interpret(ip + 4, ip + 4 + a);
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// } else {
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// interpret(ip + 4 + a, ip + 4 + a + f);
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// }
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//
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// [21] ACCEPT_N n
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//
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// stack.push(input.substring(currPos, n));
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// currPos += n;
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//
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// [22] ACCEPT_STRING s
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//
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// stack.push(consts[s]);
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// currPos += consts[s].length;
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//
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// [23] EXPECT e
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//
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// expect(consts[e]);
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//
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// Calls
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// -----
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//
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// [24] LOAD_SAVED_POS p
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//
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// savedPos = stack[p];
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//
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// [25] UPDATE_SAVED_POS
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//
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// savedPos = currPos;
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//
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// [26] CALL f, n, pc, p1, p2, ..., pN
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//
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// value = consts[f](stack[p1], ..., stack[pN]);
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// stack.pop(n);
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// stack.push(value);
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//
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// Rules
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// -----
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//
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// [27] RULE r
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//
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// stack.push(parseRule(r));
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//
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// Failure Reporting
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// -----------------
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//
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// [28] SILENT_FAILS_ON
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//
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// silentFails++;
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//
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// [29] SILENT_FAILS_OFF
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//
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// silentFails--;
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//
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// [38] EXPECT_NS_BEGIN
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//
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// expected.push({ pos: curPos, variants: [] });
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//
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// [39] EXPECT_NS_END invert
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//
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// value = expected.pop();
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// if (value.pos === expected.top().pos) {
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// if (invert) {
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// value.variants.forEach(e => { e.not = !e.not; });
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// }
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// expected.top().variants.pushAll(value.variants);
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// }
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function generateBytecode( ast ) {
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const consts = [];
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let generate;
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function addConst( value ) {
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const index = consts.indexOf( value );
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return index === -1 ? consts.push( value ) - 1 : index;
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}
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function addFunctionConst( params, code ) {
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return addConst( `function(${ params.join( ", " ) }) {${ code }}` );
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}
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function cloneEnv( env ) {
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const clone = {};
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Object.keys( env ).forEach( name => {
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clone[ name ] = env[ name ];
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} );
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return clone;
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}
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function buildSequence() {
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return Array.prototype.concat.apply( [], arguments );
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}
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function buildCondition( condCode, thenCode, elseCode ) {
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return condCode.concat(
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[ thenCode.length, elseCode.length ],
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thenCode,
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elseCode
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);
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}
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function buildLoop( condCode, bodyCode ) {
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return condCode.concat( [ bodyCode.length ], bodyCode );
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}
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function buildCall( functionIndex, delta, env, sp ) {
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const params = Object.keys( env ).map( name => sp - env[ name ] );
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return [ op.CALL, functionIndex, delta, params.length ].concat( params );
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}
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function buildSimplePredicate( expression, negative, context ) {
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return buildSequence(
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[ op.PUSH_CURR_POS ],
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[ op.EXPECT_NS_BEGIN ],
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generate( expression, {
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sp: context.sp + 1,
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env: cloneEnv( context.env ),
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action: null
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} ),
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[ op.EXPECT_NS_END, negative ? 1 : 0 ],
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buildCondition(
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[ negative ? op.IF_ERROR : op.IF_NOT_ERROR ],
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buildSequence(
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[ op.POP ],
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[ negative ? op.POP : op.POP_CURR_POS ],
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[ op.PUSH_UNDEFINED ]
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),
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buildSequence(
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[ op.POP ],
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[ negative ? op.POP_CURR_POS : op.POP ],
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[ op.PUSH_FAILED ]
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)
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)
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);
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}
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function buildSemanticPredicate( code, negative, context ) {
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const functionIndex = addFunctionConst( Object.keys( context.env ), code );
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return buildSequence(
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[ op.UPDATE_SAVED_POS ],
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buildCall( functionIndex, 0, context.env, context.sp ),
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buildCondition(
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[ op.IF ],
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buildSequence( [ op.POP ], negative ? [ op.PUSH_FAILED ] : [ op.PUSH_UNDEFINED ] ),
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buildSequence( [ op.POP ], negative ? [ op.PUSH_UNDEFINED ] : [ op.PUSH_FAILED ] )
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)
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);
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}
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function buildAppendLoop( expressionCode ) {
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return buildLoop(
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[ op.WHILE_NOT_ERROR ],
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buildSequence( [ op.APPEND ], expressionCode )
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);
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}
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generate = visitor.build( {
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grammar( node ) {
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node.rules.forEach( generate );
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node.consts = consts;
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},
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rule( node ) {
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node.bytecode = generate( node.expression, {
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sp: -1, // stack pointer
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env: { }, // mapping of label names to stack positions
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action: null // action nodes pass themselves to children here
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} );
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},
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named( node, context ) {
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const nameIndex = addConst(
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`peg$otherExpectation("${ js.stringEscape( node.name ) }")`
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);
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return buildSequence(
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[ op.EXPECT, nameIndex ],
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[ op.SILENT_FAILS_ON ],
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generate( node.expression, context ),
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[ op.SILENT_FAILS_OFF ]
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);
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},
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choice( node, context ) {
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function buildAlternativesCode( alternatives, context ) {
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return buildSequence(
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generate( alternatives[ 0 ], {
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sp: context.sp,
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env: cloneEnv( context.env ),
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action: null
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} ),
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alternatives.length < 2
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? []
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: buildCondition(
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[ op.IF_ERROR ],
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buildSequence(
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[ op.POP ],
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buildAlternativesCode( alternatives.slice( 1 ), context )
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),
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[]
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)
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);
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}
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return buildAlternativesCode( node.alternatives, context );
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},
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action( node, context ) {
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const env = cloneEnv( context.env );
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const emitCall = node.expression.type !== "sequence" || node.expression.elements.length === 0;
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const expressionCode = generate( node.expression, {
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sp: context.sp + ( emitCall ? 1 : 0 ),
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env: env,
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action: node
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} );
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const functionIndex = addFunctionConst( Object.keys( env ), node.code );
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return emitCall === false
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? expressionCode
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: buildSequence(
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[ op.PUSH_CURR_POS ],
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expressionCode,
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buildCondition(
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[ op.IF_NOT_ERROR ],
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buildSequence(
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[ op.LOAD_SAVED_POS, 1 ],
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buildCall( functionIndex, 1, env, context.sp + 2 )
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),
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[]
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),
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[ op.NIP ]
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);
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},
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sequence( node, context ) {
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function buildElementsCode( elements, context ) {
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if ( elements.length > 0 ) {
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const processedCount = node.elements.length - elements.slice( 1 ).length;
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return buildSequence(
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generate( elements[ 0 ], {
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sp: context.sp,
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env: context.env,
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action: null
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} ),
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buildCondition(
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[ op.IF_NOT_ERROR ],
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buildElementsCode( elements.slice( 1 ), {
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sp: context.sp + 1,
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env: context.env,
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action: context.action
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} ),
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buildSequence(
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processedCount > 1 ? [ op.POP_N, processedCount ] : [ op.POP ],
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[ op.POP_CURR_POS ],
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[ op.PUSH_FAILED ]
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)
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)
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);
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} else if ( context.action ) {
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const functionIndex = addFunctionConst(
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Object.keys( context.env ),
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context.action.code
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);
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return buildSequence(
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[ op.LOAD_SAVED_POS, node.elements.length ],
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buildCall(
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functionIndex,
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node.elements.length + 1,
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context.env,
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context.sp
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)
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);
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}
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return buildSequence( [ op.WRAP, node.elements.length ], [ op.NIP ] );
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}
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return buildSequence(
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[ op.PUSH_CURR_POS ],
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buildElementsCode( node.elements, {
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sp: context.sp + 1,
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env: context.env,
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action: context.action
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} )
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);
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},
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labeled( node, context ) {
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const env = cloneEnv( context.env );
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context.env[ node.label ] = context.sp + 1;
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return generate( node.expression, {
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sp: context.sp,
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env: env,
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action: null
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} );
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},
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text( node, context ) {
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return buildSequence(
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[ op.PUSH_CURR_POS ],
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generate( node.expression, {
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sp: context.sp + 1,
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env: cloneEnv( context.env ),
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action: null
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} ),
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buildCondition(
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[ op.IF_NOT_ERROR ],
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buildSequence( [ op.POP ], [ op.TEXT ] ),
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[ op.NIP ]
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)
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);
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},
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simple_and( node, context ) {
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return buildSimplePredicate( node.expression, false, context );
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},
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simple_not( node, context ) {
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return buildSimplePredicate( node.expression, true, context );
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},
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optional( node, context ) {
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return buildSequence(
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generate( node.expression, {
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sp: context.sp,
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env: cloneEnv( context.env ),
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action: null
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} ),
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buildCondition(
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[ op.IF_ERROR ],
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buildSequence( [ op.POP ], [ op.PUSH_NULL ] ),
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[]
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)
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);
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},
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zero_or_more( node, context ) {
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const expressionCode = generate( node.expression, {
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sp: context.sp + 1,
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env: cloneEnv( context.env ),
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action: null
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} );
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return buildSequence(
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[ op.PUSH_EMPTY_ARRAY ],
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expressionCode,
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buildAppendLoop( expressionCode ),
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[ op.POP ]
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);
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},
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one_or_more( node, context ) {
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const expressionCode = generate( node.expression, {
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sp: context.sp + 1,
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env: cloneEnv( context.env ),
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action: null
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} );
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return buildSequence(
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[ op.PUSH_EMPTY_ARRAY ],
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expressionCode,
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buildCondition(
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[ op.IF_NOT_ERROR ],
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buildSequence( buildAppendLoop( expressionCode ), [ op.POP ] ),
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buildSequence( [ op.POP ], [ op.POP ], [ op.PUSH_FAILED ] )
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)
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);
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},
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group( node, context ) {
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return generate( node.expression, {
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sp: context.sp,
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env: cloneEnv( context.env ),
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action: null
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} );
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},
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semantic_and( node, context ) {
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return buildSemanticPredicate( node.code, false, context );
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},
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semantic_not( node, context ) {
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return buildSemanticPredicate( node.code, true, context );
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},
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rule_ref( node ) {
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return [ op.RULE, asts.indexOfRule( ast, node.name ) ];
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},
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literal( node ) {
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if ( node.value.length > 0 ) {
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const stringIndex = addConst( `"${ js.stringEscape(
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node.ignoreCase ? node.value.toLowerCase() : node.value
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) }"` );
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const expectedIndex = addConst(
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"peg$literalExpectation("
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+ `"${ js.stringEscape( node.value ) }", `
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+ node.ignoreCase
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+ ")"
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);
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|
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// For case-sensitive strings the value must match the beginning of the
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// remaining input exactly. As a result, we can use |ACCEPT_STRING| and
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// save one |substr| call that would be needed if we used |ACCEPT_N|.
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return buildSequence(
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[ op.EXPECT, expectedIndex ],
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buildCondition(
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node.ignoreCase
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? [ op.MATCH_STRING_IC, stringIndex ]
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: [ op.MATCH_STRING, stringIndex ],
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node.ignoreCase
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? [ op.ACCEPT_N, node.value.length ]
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: [ op.ACCEPT_STRING, stringIndex ],
|
|
[ op.PUSH_FAILED ]
|
|
)
|
|
);
|
|
|
|
}
|
|
|
|
const stringIndex = addConst( "\"\"" );
|
|
return [ op.PUSH, stringIndex ];
|
|
|
|
},
|
|
|
|
class( node ) {
|
|
|
|
const regexp = "/^["
|
|
+ ( node.inverted ? "^" : "" )
|
|
+ node.parts
|
|
.map( part =>
|
|
( Array.isArray( part )
|
|
? js.regexpClassEscape( part[ 0 ] )
|
|
+ "-"
|
|
+ js.regexpClassEscape( part[ 1 ] )
|
|
: js.regexpClassEscape( part ) )
|
|
)
|
|
.join( "" )
|
|
+ "]/"
|
|
+ ( node.ignoreCase ? "i" : "" );
|
|
|
|
const parts = "["
|
|
+ node.parts
|
|
.map( part =>
|
|
( Array.isArray( part )
|
|
? `["${ js.stringEscape( part[ 0 ] ) }", "${ js.stringEscape( part[ 1 ] ) }"]`
|
|
: "\"" + js.stringEscape( part ) + "\"" )
|
|
)
|
|
.join( ", " )
|
|
+ "]";
|
|
|
|
const regexpIndex = addConst( regexp );
|
|
const expectedIndex = addConst(
|
|
"peg$classExpectation("
|
|
+ parts + ", "
|
|
+ node.inverted + ", "
|
|
+ node.ignoreCase
|
|
+ ")"
|
|
);
|
|
|
|
return buildSequence(
|
|
[ op.EXPECT, expectedIndex ],
|
|
buildCondition(
|
|
[ op.MATCH_REGEXP, regexpIndex ],
|
|
[ op.ACCEPT_N, 1 ],
|
|
[ op.PUSH_FAILED ]
|
|
)
|
|
);
|
|
|
|
},
|
|
|
|
any() {
|
|
|
|
const expectedIndex = addConst( "peg$anyExpectation()" );
|
|
|
|
return buildSequence(
|
|
[ op.EXPECT, expectedIndex ],
|
|
buildCondition(
|
|
[ op.MATCH_ANY ],
|
|
[ op.ACCEPT_N, 1 ],
|
|
[ op.PUSH_FAILED ]
|
|
)
|
|
);
|
|
|
|
}
|
|
} );
|
|
|
|
generate( ast );
|
|
|
|
}
|
|
|
|
module.exports = generateBytecode;
|