propositional/lib/syntax/equivalence.js

Propositional logic symbolic computation library

"use strict";
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var __importStar = (this && this.__importStar) || function (mod) {
    if (mod && mod.__esModule) return mod;
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    __setModuleDefault(result, mod);
    return result;
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Object.defineProperty(exports, "__esModule", { value: true });
exports.syntacticallyEquivalent = void 0;
const AST = __importStar(require("./ast"));
const token_1 = require("./token");
function syntacticallyEquivalent(e1, e2) {
    switch (true) {
        case e1 instanceof AST.BinaryExpression && e2 instanceof AST.BinaryExpression:
            return (e1.operator.type == e2.operator.type) && ((syntacticallyEquivalent(e1.left, e2.left) && syntacticallyEquivalent(e1.right, e2.right))
                || // Otherwise, except for =>, binary operators are symmetric, so can check the opposite
                    (e1.operator.type != token_1.TokenType.IF && syntacticallyEquivalent(e1.left, e2.right) && syntacticallyEquivalent(e1.right, e2.left)));
        case e1 instanceof AST.UnaryExpression && e2 instanceof AST.UnaryExpression:
            return syntacticallyEquivalent(e1.inner, e2.inner);
        case e1 instanceof AST.Literal && e2 instanceof AST.Literal:
            return (e1.value.type == e2.value.type) && (e1.value.lexeme == e2.value.lexeme);
        default:
            return false;
    }
}
exports.syntacticallyEquivalent = syntacticallyEquivalent;