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619 lines
15 KiB
JavaScript
619 lines
15 KiB
JavaScript
"use strict";
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let asts = require("../asts");
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let visitor = require("../visitor");
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let op = require("../opcodes");
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let 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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function generateBytecode(ast) {
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let consts = [];
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function addConst(value) {
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let 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(
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"function(" + params.join(", ") + ") {" + code + "}"
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);
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}
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function cloneEnv(env) {
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let 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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let 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.SILENT_FAILS_ON],
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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.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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let 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(
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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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let generate = visitor.build({
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grammar: function(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: 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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let nameIndex = addConst(
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"peg$otherExpectation(\"" + js.stringEscape(node.name) + "\")"
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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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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: cloneEnv(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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let env = cloneEnv(context.env);
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let emitCall = node.expression.type !== "sequence"
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|| node.expression.elements.length === 0;
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let 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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let functionIndex = addFunctionConst(Object.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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if (elements.length > 0) {
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let 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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let 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,
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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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let 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: 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: cloneEnv(context.env),
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action: null
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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: cloneEnv(context.env),
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action: null
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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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},
|
|
|
|
zero_or_more: function(node, context) {
|
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let expressionCode = generate(node.expression, {
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sp: context.sp + 1,
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|
env: cloneEnv(context.env),
|
|
action: null
|
|
});
|
|
|
|
return buildSequence(
|
|
[op.PUSH_EMPTY_ARRAY],
|
|
expressionCode,
|
|
buildAppendLoop(expressionCode),
|
|
[op.POP]
|
|
);
|
|
},
|
|
|
|
one_or_more: function(node, context) {
|
|
let expressionCode = generate(node.expression, {
|
|
sp: context.sp + 1,
|
|
env: cloneEnv(context.env),
|
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action: null
|
|
});
|
|
|
|
return buildSequence(
|
|
[op.PUSH_EMPTY_ARRAY],
|
|
expressionCode,
|
|
buildCondition(
|
|
[op.IF_NOT_ERROR],
|
|
buildSequence(buildAppendLoop(expressionCode), [op.POP]),
|
|
buildSequence([op.POP], [op.POP], [op.PUSH_FAILED])
|
|
)
|
|
);
|
|
},
|
|
|
|
group: function(node, context) {
|
|
return generate(node.expression, {
|
|
sp: context.sp,
|
|
env: cloneEnv(context.env),
|
|
action: null
|
|
});
|
|
},
|
|
|
|
semantic_and: function(node, context) {
|
|
return buildSemanticPredicate(node.code, false, context);
|
|
},
|
|
|
|
semantic_not: function(node, context) {
|
|
return buildSemanticPredicate(node.code, true, context);
|
|
},
|
|
|
|
rule_ref: function(node) {
|
|
return [op.RULE, asts.indexOfRule(ast, node.name)];
|
|
},
|
|
|
|
literal: function(node) {
|
|
if (node.value.length > 0) {
|
|
let stringIndex = addConst("\""
|
|
+ js.stringEscape(
|
|
node.ignoreCase ? node.value.toLowerCase() : node.value
|
|
)
|
|
+ "\""
|
|
);
|
|
let expectedIndex = addConst(
|
|
"peg$literalExpectation("
|
|
+ "\"" + js.stringEscape(node.value) + "\", "
|
|
+ node.ignoreCase
|
|
+ ")"
|
|
);
|
|
|
|
// For case-sensitive strings the value must match the beginning of the
|
|
// remaining input exactly. As a result, we can use |ACCEPT_STRING| and
|
|
// save one |substr| call that would be needed if we used |ACCEPT_N|.
|
|
return buildCondition(
|
|
node.ignoreCase
|
|
? [op.MATCH_STRING_IC, stringIndex]
|
|
: [op.MATCH_STRING, stringIndex],
|
|
node.ignoreCase
|
|
? [op.ACCEPT_N, node.value.length]
|
|
: [op.ACCEPT_STRING, stringIndex],
|
|
[op.FAIL, expectedIndex]
|
|
);
|
|
} else {
|
|
let stringIndex = addConst("\"\"");
|
|
|
|
return [op.PUSH, stringIndex];
|
|
}
|
|
},
|
|
|
|
"class": function(node) {
|
|
let 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" : "");
|
|
let parts = "["
|
|
+ node.parts.map(part =>
|
|
Array.isArray(part)
|
|
? "[\"" + js.stringEscape(part[0]) + "\", \"" + js.stringEscape(part[1]) + "\"]"
|
|
: "\"" + js.stringEscape(part) + "\""
|
|
).join(", ")
|
|
+ "]";
|
|
let regexpIndex = addConst(regexp);
|
|
let expectedIndex = addConst(
|
|
"peg$classExpectation("
|
|
+ parts + ", "
|
|
+ node.inverted + ", "
|
|
+ node.ignoreCase
|
|
+ ")"
|
|
);
|
|
|
|
return buildCondition(
|
|
[op.MATCH_REGEXP, regexpIndex],
|
|
[op.ACCEPT_N, 1],
|
|
[op.FAIL, expectedIndex]
|
|
);
|
|
},
|
|
|
|
any: function() {
|
|
let expectedIndex = addConst("peg$anyExpectation()");
|
|
|
|
return buildCondition(
|
|
[op.MATCH_ANY],
|
|
[op.ACCEPT_N, 1],
|
|
[op.FAIL, expectedIndex]
|
|
);
|
|
}
|
|
});
|
|
|
|
generate(ast);
|
|
}
|
|
|
|
module.exports = generateBytecode;
|