632 lines
16 KiB
JavaScript
632 lines
16 KiB
JavaScript
"use strict";
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var arrays = require("../../utils/arrays"),
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objects = require("../../utils/objects"),
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asts = require("../asts"),
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visitor = require("../visitor"),
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op = require("../opcodes"),
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js = require("../js");
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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] FAIL e
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*
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* stack.push(FAILED);
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* fail(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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function generateBytecode(ast) {
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var consts = [];
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function addConst(value) {
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var index = arrays.indexOf(consts, 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(
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"function(" + params.join(", ") + ") {" + code + "}"
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);
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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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var params = arrays.map(objects.values(env), function(p) { return sp - p; });
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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.SILENT_FAILS_ON],
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generate(expression, {
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sp: context.sp + 1,
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env: objects.clone(context.env),
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action: null
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}),
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[op.SILENT_FAILS_OFF],
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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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var functionIndex = addFunctionConst(objects.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(
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[op.POP],
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negative ? [op.PUSH_FAILED] : [op.PUSH_UNDEFINED]
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),
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buildSequence(
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[op.POP],
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negative ? [op.PUSH_UNDEFINED] : [op.PUSH_FAILED]
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)
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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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var generate = visitor.build({
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grammar: function(node) {
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arrays.each(node.rules, generate);
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node.consts = consts;
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},
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rule: function(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: function(node, context) {
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var nameIndex = addConst(
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'peg$otherExpectation("' + js.stringEscape(node.name) + '")'
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);
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/*
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* The code generated below is slightly suboptimal because |FAIL| pushes
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* to the stack, so we need to stick a |POP| in front of it. We lack a
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* dedicated instruction that would just report the failure and not touch
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* the stack.
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*/
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return buildSequence(
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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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buildCondition([op.IF_ERROR], [op.FAIL, nameIndex], [])
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);
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},
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choice: function(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: objects.clone(context.env),
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action: null
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}),
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alternatives.length > 1
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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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}
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return buildAlternativesCode(node.alternatives, context);
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},
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action: function(node, context) {
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var env = objects.clone(context.env),
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emitCall = node.expression.type !== "sequence"
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|| node.expression.elements.length === 0,
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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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functionIndex = addFunctionConst(objects.keys(env), node.code);
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return emitCall
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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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: expressionCode;
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},
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sequence: function(node, context) {
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function buildElementsCode(elements, context) {
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var processedCount, functionIndex;
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if (elements.length > 0) {
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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 {
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if (context.action) {
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functionIndex = addFunctionConst(
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objects.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,
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context.env,
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context.sp
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),
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[op.NIP]
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);
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} else {
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return buildSequence([op.WRAP, node.elements.length], [op.NIP]);
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}
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}
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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: function(node, context) {
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var env = objects.clone(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: function(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: objects.clone(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: function(node, context) {
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return buildSimplePredicate(node.expression, false, context);
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},
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simple_not: function(node, context) {
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return buildSimplePredicate(node.expression, true, context);
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},
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optional: function(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: objects.clone(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: function(node, context) {
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var expressionCode = generate(node.expression, {
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sp: context.sp + 1,
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env: objects.clone(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: function(node, context) {
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var expressionCode = generate(node.expression, {
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sp: context.sp + 1,
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env: objects.clone(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: function(node, context) {
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return generate(node.expression, {
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sp: context.sp,
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env: objects.clone(context.env),
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action: null
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});
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},
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semantic_and: function(node, context) {
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return buildSemanticPredicate(node.code, false, context);
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},
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semantic_not: function(node, context) {
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return buildSemanticPredicate(node.code, true, context);
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},
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rule_ref: function(node) {
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return [op.RULE, asts.indexOfRule(ast, node.name)];
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},
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literal: function(node) {
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var stringIndex, expectedIndex;
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if (node.value.length > 0) {
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stringIndex = addConst('"'
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+ js.stringEscape(
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node.ignoreCase ? node.value.toLowerCase() : node.value
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)
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+ '"'
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);
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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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*/
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return 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],
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[op.FAIL, expectedIndex]
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);
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} else {
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stringIndex = addConst('""');
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return [op.PUSH, stringIndex];
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}
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},
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"class": function(node) {
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var regexp, parts, regexpIndex, expectedIndex;
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if (node.parts.length > 0) {
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regexp = '/^['
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+ (node.inverted ? '^' : '')
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+ arrays.map(node.parts, function(part) {
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return part instanceof Array
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? js.regexpClassEscape(part[0])
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+ '-'
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+ js.regexpClassEscape(part[1])
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: js.regexpClassEscape(part);
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}).join('')
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+ ']/' + (node.ignoreCase ? 'i' : '');
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} else {
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/*
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* IE considers regexps /[]/ and /[^]/ as syntactically invalid, so we
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* translate them into equivalents it can handle.
|
|
*/
|
|
regexp = node.inverted ? '/^[\\S\\s]/' : '/^(?!)/';
|
|
}
|
|
|
|
parts = '['
|
|
+ arrays.map(node.parts, function(part) {
|
|
return part instanceof Array
|
|
? '["' + js.stringEscape(part[0]) + '", "' + js.stringEscape(part[1]) + '"]'
|
|
: '"' + js.stringEscape(part) + '"';
|
|
}).join(', ')
|
|
+ ']';
|
|
|
|
regexpIndex = addConst(regexp);
|
|
expectedIndex = addConst(
|
|
'peg$classExpectation('
|
|
+ parts + ', '
|
|
+ node.inverted + ', '
|
|
+ node.ignoreCase
|
|
+ ')'
|
|
);
|
|
|
|
return buildCondition(
|
|
[op.MATCH_REGEXP, regexpIndex],
|
|
[op.ACCEPT_N, 1],
|
|
[op.FAIL, expectedIndex]
|
|
);
|
|
},
|
|
|
|
any: function() {
|
|
var expectedIndex = addConst('peg$anyExpectation()');
|
|
|
|
return buildCondition(
|
|
[op.MATCH_ANY],
|
|
[op.ACCEPT_N, 1],
|
|
[op.FAIL, expectedIndex]
|
|
);
|
|
}
|
|
});
|
|
|
|
generate(ast);
|
|
}
|
|
|
|
module.exports = generateBytecode;
|