diff options
Diffstat (limited to 'js/scripting-lang/lang.js')
| -rw-r--r-- | js/scripting-lang/lang.js | 1975 |
1 files changed, 1698 insertions, 277 deletions
diff --git a/js/scripting-lang/lang.js b/js/scripting-lang/lang.js index f91f842..d3bc0b5 100644 --- a/js/scripting-lang/lang.js +++ b/js/scripting-lang/lang.js @@ -1,320 +1,1741 @@ -// The goal here is less to make anything useful...or even something that works, but to learn what parts an interpreted languages needs to have to function. +// Cross-platform scripting language implementation +// Supports Node.js, Bun, and browser environments -// Define the types of tokens -const TokenType = { - NUMBER: 'NUMBER', - PLUS: 'PLUS', - IDENTIFIER: 'IDENTIFIER', - ASSIGNMENT: 'ASSIGNMENT', - FUNCTION: 'FUNCTION', - LEFT_PAREN: 'LEFT_PAREN', - RIGHT_PAREN: 'RIGHT_PAREN', - LEFT_BRACE: 'LEFT_BRACE', - RIGHT_BRACE: 'RIGHT_BRACE', - SEMICOLON: 'SEMICOLON', -}; - -// Lexer -function lexer(input) { - const tokens = []; - let current = 0; - - while (current < input.length) { - let char = input[current]; +import { lexer, TokenType } from './lexer.js'; +import { parser } from './parser.js'; - if (/\d/.test(char)) { - let value = ''; - while (/\d/.test(char)) { - value += char; - char = input[++current]; - } - tokens.push({ - type: TokenType.NUMBER, - value - }); - continue; +/** + * Initializes the standard library in the provided scope. + * + * @param {Object} scope - The global scope object to inject functions into + * @description Injects higher-order functions and combinator functions into the interpreter's global scope. + * These functions provide functional programming utilities and implement the combinator foundation + * that eliminates parsing ambiguity by translating all operations to function calls. + * + * The standard library includes: + * - Higher-order functions (map, compose, pipe, apply, filter, reduce, fold, curry) + * - Arithmetic combinators (add, subtract, multiply, divide, modulo, power, negate) + * - Comparison combinators (equals, notEquals, lessThan, greaterThan, lessEqual, greaterEqual) + * - Logical combinators (logicalAnd, logicalOr, logicalXor, logicalNot) + * - Enhanced combinators (identity, constant, flip, on, both, either) + * + * This approach ensures that user code can access these functions as if they were built-in, + * without special syntax or reserved keywords. The combinator foundation allows the parser + * to translate all operators to function calls, eliminating ambiguity while preserving syntax. + * + * Functions are written to check argument types at runtime since the language is dynamically + * typed and does not enforce arity or types at parse time. + */ +function initializeStandardLibrary(scope) { + /** + * Map: Apply a function to a value + * @param {Function} f - Function to apply + * @param {*} x - Value to apply function to + * @returns {*} Result of applying f to x + * @throws {Error} When first argument is not a function + */ + scope.map = function(f, x) { + if (typeof f === 'function') { + return f(x); + } else { + throw new Error('map: first argument must be a function'); } - - if (char === '+') { - tokens.push({ - type: TokenType.PLUS - }); - current++; - continue; - } - - if (/[a-z]/i.test(char)) { - let value = ''; - while (/[a-z]/i.test(char)) { - value += char; - char = input[++current]; + }; + + /** + * Compose: Compose two functions (f ∘ g)(x) = f(g(x)) + * @param {Function} f - Outer function + * @param {Function} g - Inner function + * @param {*} [x] - Optional argument to apply composed function to + * @returns {Function|*} Either a composed function or the result of applying it + * @throws {Error} When first two arguments are not functions + */ + scope.compose = function(f, g, x) { + if (typeof f === 'function' && typeof g === 'function') { + if (arguments.length === 3) { + return f(g(x)); + } else { + return function(x) { + return f(g(x)); + }; } - tokens.push({ - type: TokenType.IDENTIFIER, - value - }); - continue; - } - - if (char === ':') { - tokens.push({ - type: TokenType.ASSIGNMENT - }); - current++; - continue; + } else { + throw new Error('compose: first two arguments must be functions'); } - - if (char === '=') { - tokens.push({ - type: TokenType.EQUAL - }); - current++; - continue; - } - - if (input.slice(current, current + 2) === 'if') { - tokens.push({ - type: TokenType.IF - }); - current += 2; - continue; - } - - if (input.slice(current, current + 4) === 'else') { - tokens.push({ - type: TokenType.ELSE - }); - current += 4; - continue; - } - - if (char === '(') { - tokens.push({ - type: TokenType.LEFT_PAREN - }); - current++; - continue; - } - - if (char === ')') { - tokens.push({ - type: TokenType.RIGHT_PAREN - }); - current++; - continue; - } - - if (char === '{') { - tokens.push({ - type: TokenType.LEFT_BRACE - }); - current++; - continue; + }; + + /** + * Curry: Apply a function to arguments (simplified currying) + * @param {Function} f - Function to curry + * @param {*} x - First argument + * @param {*} y - Second argument + * @returns {*} Result of applying f to x and y + * @throws {Error} When first argument is not a function + */ + scope.curry = function(f, x, y) { + if (typeof f === 'function') { + return f(x, y); + } else { + throw new Error('curry: first argument must be a function'); } - - if (char === '}') { - tokens.push({ - type: TokenType.RIGHT_BRACE - }); - current++; - continue; + }; + + /** + * Apply: Apply a function to an argument (explicit function application) + * @param {Function} f - Function to apply + * @param {*} x - Argument to apply function to + * @returns {*} Result of applying f to x + * @throws {Error} When first argument is not a function + */ + scope.apply = function(f, x) { + if (typeof f === 'function') { + return f(x); + } else { + throw new Error('apply: first argument must be a function'); } - - if (input.slice(current, current + 8) === 'function') { - tokens.push({ - type: TokenType.FUNCTION - }); - current += 8; - continue; + }; + + /** + * Pipe: Compose functions in left-to-right order (opposite of compose) + * @param {Function} f - First function + * @param {Function} g - Second function + * @param {*} [x] - Optional argument to apply piped function to + * @returns {Function|*} Either a piped function or the result of applying it + * @throws {Error} When first two arguments are not functions + */ + scope.pipe = function(f, g, x) { + if (typeof f === 'function' && typeof g === 'function') { + if (arguments.length === 3) { + return g(f(x)); + } else { + return function(x) { + return g(f(x)); + }; + } + } else { + throw new Error('pipe: first two arguments must be functions'); } - - if (char === ';') { - tokens.push({ type: TokenType.SEMICOLON }); - current++; - continue; + }; + + /** + * Filter: Filter a value based on a predicate + * @param {Function} p - Predicate function + * @param {*} x - Value to test + * @returns {*|0} The value if predicate is true, 0 otherwise + * @throws {Error} When first argument is not a function + */ + scope.filter = function(p, x) { + if (typeof p === 'function') { + return p(x) ? x : 0; + } else { + throw new Error('filter: first argument must be a function'); } - - current++; - } - - return tokens; -} - -// Parser -function parser(tokens) { - let current = 0; - - function walk() { - if (current >= tokens.length) { - return null; // Return null when there are no more tokens + }; + + /** + * Reduce: Reduce two values using a binary function + * @param {Function} f - Binary function + * @param {*} init - Initial value + * @param {*} x - Second value + * @returns {*} Result of applying f to init and x + * @throws {Error} When first argument is not a function + */ + scope.reduce = function(f, init, x) { + if (typeof f === 'function') { + return f(init, x); + } else { + throw new Error('reduce: first argument must be a function'); } - - let token = tokens[current]; - - if (token.type === TokenType.NUMBER) { - current++; - return { - type: 'NumberLiteral', - value: token.value, - }; + }; + + /** + * Fold: Same as reduce, but more explicit about the folding direction + * @param {Function} f - Binary function + * @param {*} init - Initial value + * @param {*} x - Second value + * @returns {*} Result of applying f to init and x + * @throws {Error} When first argument is not a function + */ + scope.fold = function(f, init, x) { + if (typeof f === 'function') { + return f(init, x); + } else { + throw new Error('fold: first argument must be a function'); } - - if (token.type === TokenType.PLUS) { - current++; - return { - type: 'PlusExpression', - left: walk(), - right: walk(), - }; + }; + + // ===== ARITHMETIC COMBINATORS ===== + + /** + * Add: Add two numbers + * @param {number} x - First number + * @param {number} y - Second number + * @returns {number} Sum of x and y + */ + scope.add = function(x, y) { + return x + y; + }; + + /** + * Subtract: Subtract second number from first + * @param {number} x - First number + * @param {number} y - Second number + * @returns {number} Difference of x and y + */ + scope.subtract = function(x, y) { + return x - y; + }; + + /** + * Multiply: Multiply two numbers + * @param {number} x - First number + * @param {number} y - Second number + * @returns {number} Product of x and y + */ + scope.multiply = function(x, y) { + return x * y; + }; + + /** + * Divide: Divide first number by second + * @param {number} x - First number + * @param {number} y - Second number + * @returns {number} Quotient of x and y + * @throws {Error} When second argument is zero + */ + scope.divide = function(x, y) { + if (y === 0) { + throw new Error('Division by zero'); } - - if (token.type === TokenType.IDENTIFIER) { - current++; - return { - type: 'Identifier', - value: token.value, + return x / y; + }; + + /** + * Modulo: Get remainder of division + * @param {number} x - First number + * @param {number} y - Second number + * @returns {number} Remainder of x divided by y + */ + scope.modulo = function(x, y) { + return x % y; + }; + + /** + * Power: Raise first number to power of second + * @param {number} x - Base number + * @param {number} y - Exponent + * @returns {number} x raised to the power of y + */ + scope.power = function(x, y) { + return Math.pow(x, y); + }; + + /** + * Negate: Negate a number + * @param {number} x - Number to negate + * @returns {number} Negated value of x + */ + scope.negate = function(x) { + return -x; + }; + + // ===== COMPARISON COMBINATORS ===== + + /** + * Equals: Check if two values are equal + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x equals y + */ + scope.equals = function(x, y) { + return x === y; + }; + + /** + * NotEquals: Check if two values are not equal + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x does not equal y + */ + scope.notEquals = function(x, y) { + return x !== y; + }; + + /** + * LessThan: Check if first value is less than second + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x < y + */ + scope.lessThan = function(x, y) { + return x < y; + }; + + /** + * GreaterThan: Check if first value is greater than second + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x > y + */ + scope.greaterThan = function(x, y) { + return x > y; + }; + + /** + * LessEqual: Check if first value is less than or equal to second + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x <= y + */ + scope.lessEqual = function(x, y) { + return x <= y; + }; + + /** + * GreaterEqual: Check if first value is greater than or equal to second + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if x >= y + */ + scope.greaterEqual = function(x, y) { + return x >= y; + }; + + // ===== LOGICAL COMBINATORS ===== + + /** + * LogicalAnd: Logical AND of two values + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if both x and y are truthy + */ + scope.logicalAnd = function(x, y) { + return !!(x && y); + }; + + /** + * LogicalOr: Logical OR of two values + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if either x or y is truthy + */ + scope.logicalOr = function(x, y) { + return !!(x || y); + }; + + /** + * LogicalXor: Logical XOR of two values + * @param {*} x - First value + * @param {*} y - Second value + * @returns {boolean} True if exactly one of x or y is truthy + */ + scope.logicalXor = function(x, y) { + return !!((x && !y) || (!x && y)); + }; + + /** + * LogicalNot: Logical NOT of a value + * @param {*} x - Value to negate + * @returns {boolean} True if x is falsy, false if x is truthy + */ + scope.logicalNot = function(x) { + return !x; + }; + + // ===== ASSIGNMENT COMBINATOR ===== + + /** + * Assign: Assign a value to a variable name + * @param {string} name - Variable name + * @param {*} value - Value to assign + * @returns {*} The assigned value + * @throws {Error} When trying to reassign an immutable variable + * @note This function needs access to the global scope, so it will be + * set up during interpreter initialization + */ + // Note: assign will be set up in the interpreter with access to globalScope + + // ===== ENHANCED HIGHER-ORDER COMBINATORS ===== + + /** + * Identity: Return the input unchanged + * @param {*} x - Any value + * @returns {*} The same value + */ + scope.identity = function(x) { + return x; + }; + + /** + * Constant: Create a function that always returns the same value + * @param {*} x - Value to return + * @param {*} [y] - Optional second argument (ignored) + * @returns {*} The value x, or a function if only one argument provided + */ + scope.constant = function(x, y) { + if (arguments.length === 2) { + return x; + } else { + return function(y) { + return x; }; } - - if (token.type === TokenType.ASSIGNMENT) { - current++; - return { - type: 'AssignmentExpression', - name: tokens[current - 2].value, - value: walk(), + }; + + /** + * Flip: Flip the order of arguments for a binary function + * @param {Function} f - Binary function + * @param {*} [x] - Optional first argument + * @param {*} [y] - Optional second argument + * @returns {Function|*} Function with flipped argument order, or result if arguments provided + */ + scope.flip = function(f, x, y) { + if (arguments.length === 3) { + return f(y, x); + } else { + return function(x, y) { + return f(y, x); }; } + }; + + /** + * On: Apply a function to the results of another function + * @param {Function} f - Outer function + * @param {Function} g - Inner function + * @returns {Function} Function that applies f to the results of g + */ + scope.on = function(f, g) { + return function(x, y) { + return f(g(x), g(y)); + }; + }; + + /** + * Both: Check if both predicates are true + * @param {Function} f - First predicate + * @param {Function} g - Second predicate + * @returns {Function} Function that returns true if both predicates are true + */ + scope.both = function(f, g) { + return function(x) { + return f(x) && g(x); + }; + }; + + /** + * Either: Check if either predicate is true + * @param {Function} f - First predicate + * @param {Function} g - Second predicate + * @returns {Function} Function that returns true if either predicate is true + */ + scope.either = function(f, g) { + return function(x) { + return f(x) || g(x); + }; + }; +} - if (token.type === TokenType.IF) { - current++; - let node = { - type: 'IfExpression', - test: walk(), - consequent: walk(), - alternate: tokens[current].type === TokenType.ELSE ? (current++, walk()) : null, - }; - return node; +/** + * Interpreter: Walks the AST and evaluates each node. + * + * @param {Object} ast - Abstract Syntax Tree to evaluate + * @returns {*} The result of evaluating the AST, or a Promise for async operations + * @throws {Error} For evaluation errors like division by zero, undefined variables, etc. + * + * @description Evaluates an AST by walking through each node and performing the + * corresponding operations. Manages scope, handles function calls, and supports + * both synchronous and asynchronous operations. + * + * The interpreter implements a combinator-based architecture where all operations + * are translated to function calls to standard library combinators. This eliminates + * parsing ambiguity while preserving the original syntax. The parser generates + * FunctionCall nodes for operators (e.g., x + y becomes add(x, y)), and the + * interpreter executes these calls using the combinator functions in the global scope. + * + * The interpreter uses a global scope for variable storage and function definitions. + * Each function call creates a new scope (using prototypal inheritance) to implement + * lexical scoping. Immutability is enforced by preventing reassignment in the + * global scope. + * + * The interpreter is split into three functions: evalNode (global), + * localEvalNodeWithScope (for function bodies), and localEvalNode (for internal + * recursion). This separation allows for correct scope handling and easier debugging. + * + * Recursive function support is implemented using a forward declaration pattern: + * a placeholder function is created in the global scope before evaluation, allowing + * the function body to reference itself during evaluation. + */ +function interpreter(ast) { + const globalScope = {}; + initializeStandardLibrary(globalScope); + + // Debug: Check if combinators are available + if (process.env.DEBUG) { + console.log('[DEBUG] Available functions in global scope:', Object.keys(globalScope)); + console.log('[DEBUG] add function exists:', typeof globalScope.add === 'function'); + console.log('[DEBUG] subtract function exists:', typeof globalScope.subtract === 'function'); + } + + // Reset call stack tracker at the start of interpretation + callStackTracker.reset(); + + /** + * Evaluates AST nodes in the global scope. + * + * @param {Object} node - AST node to evaluate + * @returns {*} The result of evaluating the node + * @throws {Error} For evaluation errors + * + * @description Main evaluation function that handles all node types in the + * global scope context. This function processes the core language constructs + * and delegates to combinator functions for all operations. + * + * The function implements the forward declaration pattern for recursive functions: + * when a function assignment is detected, a placeholder is created in the global + * scope before evaluation, allowing the function body to reference itself. + */ + function evalNode(node) { + callStackTracker.push('evalNode', node?.type || 'unknown'); + + try { + if (!node) { + return undefined; + } + switch (node.type) { + case 'NumberLiteral': + return parseFloat(node.value); + case 'StringLiteral': + return node.value; + case 'BooleanLiteral': + return node.value; + case 'PlusExpression': + return evalNode(node.left) + evalNode(node.right); + case 'MinusExpression': + return evalNode(node.left) - evalNode(node.right); + case 'MultiplyExpression': + return evalNode(node.left) * evalNode(node.right); + case 'DivideExpression': + const divisor = evalNode(node.right); + if (divisor === 0) { + throw new Error('Division by zero'); + } + return evalNode(node.left) / evalNode(node.right); + case 'ModuloExpression': + return evalNode(node.left) % evalNode(node.right); + case 'PowerExpression': + return Math.pow(evalNode(node.left), evalNode(node.right)); + case 'EqualsExpression': + return evalNode(node.left) === evalNode(node.right); + case 'LessThanExpression': + return evalNode(node.left) < evalNode(node.right); + case 'GreaterThanExpression': + return evalNode(node.left) > evalNode(node.right); + case 'LessEqualExpression': + return evalNode(node.left) <= evalNode(node.right); + case 'GreaterEqualExpression': + return evalNode(node.left) >= evalNode(node.right); + case 'NotEqualExpression': + return evalNode(node.left) !== evalNode(node.right); + case 'AndExpression': + return !!(evalNode(node.left) && evalNode(node.right)); + case 'OrExpression': + return !!(evalNode(node.left) || evalNode(node.right)); + case 'XorExpression': + const leftVal = evalNode(node.left); + const rightVal = evalNode(node.right); + return !!((leftVal && !rightVal) || (!leftVal && rightVal)); + case 'NotExpression': + return !evalNode(node.operand); + case 'UnaryMinusExpression': + return -evalNode(node.operand); + case 'TableLiteral': + const table = {}; + let arrayIndex = 1; + + for (const entry of node.entries) { + if (entry.key === null) { + // Array-like entry: {1, 2, 3} + table[arrayIndex] = evalNode(entry.value); + arrayIndex++; + } else { + // Key-value entry: {name: "Alice", age: 30} + let key; + if (entry.key.type === 'Identifier') { + // Convert identifier keys to strings + key = entry.key.value; + } else { + // For other key types (numbers, strings), evaluate normally + key = evalNode(entry.key); + } + const value = evalNode(entry.value); + table[key] = value; + } + } + + return table; + case 'TableAccess': + const tableValue = evalNode(node.table); + let keyValue; + + // Handle different key types + if (node.key.type === 'Identifier') { + // For dot notation, use the identifier name as the key + keyValue = node.key.value; + } else { + // For bracket notation, evaluate the key expression + keyValue = evalNode(node.key); + } + + if (typeof tableValue !== 'object' || tableValue === null) { + throw new Error('Cannot access property of non-table value'); + } + + if (tableValue[keyValue] === undefined) { + throw new Error(`Key '${keyValue}' not found in table`); + } + + return tableValue[keyValue]; + case 'AssignmentExpression': + // Prevent reassignment of standard library functions + if (globalScope.hasOwnProperty(node.name)) { + throw new Error(`Cannot reassign immutable variable: ${node.name}`); + } + + // Check if this is a function assignment for potential recursion + if (node.value.type === 'FunctionDefinition' || node.value.type === 'FunctionDeclaration') { + // Create a placeholder function that will be replaced + let placeholder = function(...args) { + // This should never be called, but if it is, it means we have a bug + throw new Error(`Function ${node.name} is not yet fully defined`); + }; + + // Store the placeholder in global scope + globalScope[node.name] = placeholder; + + // Now evaluate the function definition with access to the placeholder + const actualFunction = evalNode(node.value); + + // Replace the placeholder with the actual function + globalScope[node.name] = actualFunction; + return; + } + + const value = evalNode(node.value); + globalScope[node.name] = value; + return; + case 'Assignment': + // Prevent reassignment of standard library functions + if (globalScope.hasOwnProperty(node.identifier)) { + throw new Error(`Cannot reassign immutable variable: ${node.identifier}`); + } + + // Check if this is a function assignment for potential recursion + if (node.value.type === 'FunctionDefinition' || node.value.type === 'FunctionDeclaration') { + // Create a placeholder function that will be replaced + let placeholder = function(...args) { + // This should never be called, but if it is, it means we have a bug + throw new Error(`Function ${node.identifier} is not yet fully defined`); + }; + + // Store the placeholder in global scope + globalScope[node.identifier] = placeholder; + + // Now evaluate the function definition with access to the placeholder + const actualFunction = evalNode(node.value); + + // Replace the placeholder with the actual function + globalScope[node.identifier] = actualFunction; + return; + } + + const assignmentValue = evalNode(node.value); + globalScope[node.identifier] = assignmentValue; + return; + case 'Identifier': + const identifierValue = globalScope[node.value]; + if (identifierValue === undefined) { + throw new Error(`Variable ${node.value} is not defined`); + } + return identifierValue; + case 'FunctionDeclaration': + // For anonymous functions, the name comes from the assignment + // The function itself doesn't have a name, so we just return + // The assignment will handle storing it in the global scope + return function(...args) { + callStackTracker.push('FunctionCall', node.params.join(',')); + try { + let localScope = Object.create(globalScope); + for (let i = 0; i < node.params.length; i++) { + localScope[node.params[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, localScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionDefinition': + // Create a function from the function definition + return function(...args) { + callStackTracker.push('FunctionCall', node.parameters.join(',')); + try { + let localScope = Object.create(globalScope); + for (let i = 0; i < node.parameters.length; i++) { + localScope[node.parameters[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, localScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionCall': + let funcToCall; + if (typeof node.name === 'string') { + // Regular function call with string name + funcToCall = globalScope[node.name]; + if (process.env.DEBUG) { + console.log(`[DEBUG] FunctionCall: looking up function '${node.name}' in globalScope, found:`, typeof funcToCall); + } + } else if (node.name.type === 'Identifier') { + // Function call with identifier + funcToCall = globalScope[node.name.value]; + if (process.env.DEBUG) { + console.log(`[DEBUG] FunctionCall: looking up function '${node.name.value}' in globalScope, found:`, typeof funcToCall); + } + } else { + // Function call from expression (e.g., parenthesized function, higher-order) + funcToCall = evalNode(node.name); + if (process.env.DEBUG) { + console.log(`[DEBUG] FunctionCall: evaluated function expression, found:`, typeof funcToCall); + } + } + + if (funcToCall instanceof Function) { + let args = node.args.map(evalNode); + if (process.env.DEBUG) { + console.log(`[DEBUG] FunctionCall: calling function with args:`, args); + } + return funcToCall(...args); + } + throw new Error(`Function is not defined or is not callable`); + case 'WhenExpression': + // Handle both single values and arrays of values + const whenValues = Array.isArray(node.value) + ? node.value.map(evalNode) + : [evalNode(node.value)]; + + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: whenValues =`, whenValues); + } + + for (const caseItem of node.cases) { + // Handle both single patterns and arrays of patterns + const patterns = caseItem.pattern.map(evalNode); + + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: patterns =`, patterns); + } + + // Check if patterns match the values + let matches = true; + if (whenValues.length !== patterns.length) { + matches = false; + } else { + for (let i = 0; i < whenValues.length; i++) { + const value = whenValues[i]; + const pattern = patterns[i]; + + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: comparing value ${value} with pattern ${pattern}`); + } + + if (pattern === true) { // Wildcard pattern + // Wildcard always matches + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: wildcard matches`); + } + continue; + } else if (value !== pattern) { + matches = false; + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: pattern does not match`); + } + break; + } else { + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: pattern matches`); + } + } + } + } + + if (process.env.DEBUG) { + console.log(`[DEBUG] WhenExpression: case matches = ${matches}`); + } + + if (matches) { + const results = caseItem.result.map(evalNode); + if (results.length === 1) { + return results[0]; + } + return results.join(' '); + } + } + throw new Error('No matching pattern found'); + case 'WildcardPattern': + return true; + case 'IOInExpression': + const readline = require('readline'); + const rl = readline.createInterface({ + input: process.stdin, + output: process.stdout + }); + + return new Promise((resolve) => { + rl.question('', (input) => { + rl.close(); + const num = parseInt(input); + resolve(isNaN(num) ? input : num); + }); + }); + case 'IOOutExpression': + const outputValue = evalNode(node.value); + console.log(outputValue); + return outputValue; + case 'IOAssertExpression': + const assertionValue = evalNode(node.value); + if (!assertionValue) { + throw new Error('Assertion failed'); + } + return assertionValue; + case 'FunctionReference': + const functionValue = globalScope[node.name]; + if (functionValue === undefined) { + throw new Error(`Function ${node.name} is not defined`); + } + if (typeof functionValue !== 'function') { + throw new Error(`${node.name} is not a function`); + } + return functionValue; + case 'ArrowExpression': + // Arrow expressions are function bodies that should be evaluated + return evalNode(node.body); + default: + throw new Error(`Unknown node type: ${node.type}`); + } + } finally { + callStackTracker.pop(); } + } - if (token.type === TokenType.FUNCTION) { - current++; - let node = { - type: 'FunctionDeclaration', - name: tokens[current++].value, - params: [], - body: [], - }; - while (tokens[current].type !== TokenType.RIGHT_PAREN) { - node.params.push(tokens[current++].value); + /** + * Evaluates AST nodes in a local scope with access to parent scope. + * + * @param {Object} node - AST node to evaluate + * @param {Object} scope - Local scope object (prototypally inherits from global) + * @returns {*} The result of evaluating the node + * @throws {Error} For evaluation errors + * + * @description Used for evaluating function bodies and other expressions + * that need access to both local and global variables. This function implements + * lexical scoping by creating a local scope that prototypally inherits from + * the global scope, allowing access to both local parameters and global functions. + * + * The function handles the same node types as evalNode but uses the local scope + * for variable lookups. It also implements the forward declaration pattern for + * recursive functions, ensuring that function definitions can reference themselves + * during evaluation. + * + * This separation of global and local evaluation allows for proper scope management + * and prevents variable name conflicts between function parameters and global variables. + */ + const localEvalNodeWithScope = (node, scope) => { + callStackTracker.push('localEvalNodeWithScope', node?.type || 'unknown'); + + try { + if (!node) { + return undefined; } - current++; // Skip right paren - while (tokens[current].type !== TokenType.RIGHT_BRACE) { - node.body.push(walk()); + switch (node.type) { + case 'NumberLiteral': + return parseFloat(node.value); + case 'StringLiteral': + return node.value; + case 'BooleanLiteral': + return node.value; + case 'PlusExpression': + return localEvalNodeWithScope(node.left, scope) + localEvalNodeWithScope(node.right, scope); + case 'MinusExpression': + return localEvalNodeWithScope(node.left, scope) - localEvalNodeWithScope(node.right, scope); + case 'MultiplyExpression': + return localEvalNodeWithScope(node.left, scope) * localEvalNodeWithScope(node.right, scope); + case 'DivideExpression': + const divisor = localEvalNodeWithScope(node.right, scope); + if (divisor === 0) { + throw new Error('Division by zero'); + } + return localEvalNodeWithScope(node.left, scope) / localEvalNodeWithScope(node.right, scope); + case 'ModuloExpression': + return localEvalNodeWithScope(node.left, scope) % localEvalNodeWithScope(node.right, scope); + case 'PowerExpression': + return Math.pow(localEvalNodeWithScope(node.left, scope), localEvalNodeWithScope(node.right, scope)); + case 'EqualsExpression': + return localEvalNodeWithScope(node.left, scope) === localEvalNodeWithScope(node.right, scope); + case 'LessThanExpression': + return localEvalNodeWithScope(node.left, scope) < localEvalNodeWithScope(node.right, scope); + case 'GreaterThanExpression': + return localEvalNodeWithScope(node.left, scope) > localEvalNodeWithScope(node.right, scope); + case 'LessEqualExpression': + return localEvalNodeWithScope(node.left, scope) <= localEvalNodeWithScope(node.right, scope); + case 'GreaterEqualExpression': + return localEvalNodeWithScope(node.left, scope) >= localEvalNodeWithScope(node.right, scope); + case 'NotEqualExpression': + return localEvalNodeWithScope(node.left, scope) !== localEvalNodeWithScope(node.right, scope); + case 'AndExpression': + return !!(localEvalNodeWithScope(node.left, scope) && localEvalNodeWithScope(node.right, scope)); + case 'OrExpression': + return !!(localEvalNodeWithScope(node.left, scope) || localEvalNodeWithScope(node.right, scope)); + case 'XorExpression': + const leftVal = localEvalNodeWithScope(node.left, scope); + const rightVal = localEvalNodeWithScope(node.right, scope); + return !!((leftVal && !rightVal) || (!leftVal && rightVal)); + case 'NotExpression': + return !localEvalNodeWithScope(node.operand, scope); + case 'UnaryMinusExpression': + return -localEvalNodeWithScope(node.operand, scope); + case 'TableLiteral': + const table = {}; + let arrayIndex = 1; + + for (const entry of node.entries) { + if (entry.key === null) { + // Array-like entry: {1, 2, 3} + table[arrayIndex] = localEvalNodeWithScope(entry.value, scope); + arrayIndex++; + } else { + // Key-value entry: {name: "Alice", age: 30} + let key; + if (entry.key.type === 'Identifier') { + // Convert identifier keys to strings + key = entry.key.value; + } else { + // For other key types (numbers, strings), evaluate normally + key = localEvalNodeWithScope(entry.key, scope); + } + const value = localEvalNodeWithScope(entry.value, scope); + table[key] = value; + } + } + + return table; + case 'TableAccess': + const tableValue = localEvalNodeWithScope(node.table, scope); + let keyValue; + + // Handle different key types + if (node.key.type === 'Identifier') { + // For dot notation, use the identifier name as the key + keyValue = node.key.value; + } else { + // For bracket notation, evaluate the key expression + keyValue = localEvalNodeWithScope(node.key, scope); + } + + if (typeof tableValue !== 'object' || tableValue === null) { + throw new Error('Cannot access property of non-table value'); + } + + if (tableValue[keyValue] === undefined) { + throw new Error(`Key '${keyValue}' not found in table`); + } + + return tableValue[keyValue]; + case 'AssignmentExpression': + // Prevent reassignment of standard library functions + if (globalScope.hasOwnProperty(node.name)) { + throw new Error(`Cannot reassign immutable variable: ${node.name}`); + } + + // Check if this is a function assignment for potential recursion + if (node.value.type === 'FunctionDefinition' || node.value.type === 'FunctionDeclaration') { + // Create a placeholder function that will be replaced + let placeholder = function(...args) { + // This should never be called, but if it is, it means we have a bug + throw new Error(`Function ${node.name} is not yet fully defined`); + }; + + // Store the placeholder in global scope + globalScope[node.name] = placeholder; + + // Now evaluate the function definition with access to the placeholder + const actualFunction = localEvalNodeWithScope(node.value, scope); + + // Replace the placeholder with the actual function + globalScope[node.name] = actualFunction; + return; + } + + globalScope[node.name] = localEvalNodeWithScope(node.value, scope); + return; + case 'Identifier': + // First check local scope, then global scope + if (scope && scope.hasOwnProperty(node.value)) { + return scope[node.value]; + } + const identifierValue = globalScope[node.value]; + if (identifierValue === undefined && node.value) { + return node.value; + } + return identifierValue; + case 'FunctionDeclaration': + // For anonymous functions, the name comes from the assignment + // The function itself doesn't have a name, so we just return + // The assignment will handle storing it in the global scope + return function(...args) { + callStackTracker.push('FunctionCall', node.params.join(',')); + try { + let nestedScope = Object.create(globalScope); + for (let i = 0; i < node.params.length; i++) { + nestedScope[node.params[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, nestedScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionDefinition': + // Create a function from the function definition + return function(...args) { + callStackTracker.push('FunctionCall', node.parameters.join(',')); + try { + let nestedScope = Object.create(globalScope); + for (let i = 0; i < node.parameters.length; i++) { + nestedScope[node.parameters[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, nestedScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionCall': + let localFunc; + if (typeof node.name === 'string') { + // Regular function call with string name + localFunc = globalScope[node.name]; + } else if (node.name.type === 'Identifier') { + // Function call with identifier + localFunc = globalScope[node.name.value]; + } else { + // Function call from expression (e.g., parenthesized function, higher-order) + localFunc = localEvalNodeWithScope(node.name, scope); + } + + if (localFunc instanceof Function) { + let args = node.args.map(arg => localEvalNodeWithScope(arg, scope)); + return localFunc(...args); + } + throw new Error(`Function is not defined or is not callable`); + case 'WhenExpression': + // Handle both single values and arrays of values + const whenValues = Array.isArray(node.value) + ? node.value.map(val => localEvalNodeWithScope(val, scope)) + : [localEvalNodeWithScope(node.value, scope)]; + + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: whenValues =`, whenValues); + } + + for (const caseItem of node.cases) { + // Handle both single patterns and arrays of patterns + const patterns = caseItem.pattern.map(pat => localEvalNodeWithScope(pat, scope)); + + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: patterns =`, patterns); + } + + // Check if patterns match the values + let matches = true; + if (whenValues.length !== patterns.length) { + matches = false; + } else { + for (let i = 0; i < whenValues.length; i++) { + const value = whenValues[i]; + const pattern = patterns[i]; + + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: comparing value ${value} with pattern ${pattern}`); + } + + if (pattern === true) { // Wildcard pattern + // Wildcard always matches + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: wildcard matches`); + } + continue; + } else if (value !== pattern) { + matches = false; + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: pattern does not match`); + } + break; + } else { + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: pattern matches`); + } + } + } + } + + if (process.env.DEBUG) { + console.log(`[DEBUG] localEvalNodeWithScope WhenExpression: case matches = ${matches}`); + } + + if (matches) { + const results = caseItem.result.map(res => localEvalNodeWithScope(res, scope)); + if (results.length === 1) { + return results[0]; + } + return results.join(' '); + } + } + throw new Error('No matching pattern found'); + case 'WildcardPattern': + return true; + case 'IOInExpression': + const readline = require('readline'); + const rl = readline.createInterface({ + input: process.stdin, + output: process.stdout + }); + + return new Promise((resolve) => { + rl.question('', (input) => { + rl.close(); + const num = parseInt(input); + resolve(isNaN(num) ? input : num); + }); + }); + case 'IOOutExpression': + const localOutputValue = localEvalNodeWithScope(node.value, scope); + console.log(localOutputValue); + return localOutputValue; + case 'IOAssertExpression': + const localAssertionValue = localEvalNodeWithScope(node.value, scope); + if (!localAssertionValue) { + throw new Error('Assertion failed'); + } + return localAssertionValue; + case 'FunctionReference': + const localFunctionValue = globalScope[node.name]; + if (localFunctionValue === undefined) { + throw new Error(`Function ${node.name} is not defined`); + } + if (typeof localFunctionValue !== 'function') { + throw new Error(`${node.name} is not a function`); + } + return localFunctionValue; + case 'ArrowExpression': + // Arrow expressions are function bodies that should be evaluated + return localEvalNodeWithScope(node.body, scope); + default: + throw new Error(`Unknown node type: ${node.type}`); } - current++; // Skip right brace - return node; + } finally { + callStackTracker.pop(); } + }; - if (token.type === TokenType.IDENTIFIER && tokens[current + 1].type === TokenType.LEFT_PAREN) { - current++; - let node = { - type: 'FunctionCall', - name: token.value, - args: [], - }; - current++; // Skip left paren - while (tokens[current].type !== TokenType.RIGHT_PAREN) { - node.args.push(walk()); + /** + * Evaluates AST nodes in the global scope (internal recursion helper). + * + * @param {Object} node - AST node to evaluate + * @returns {*} The result of evaluating the node + * @throws {Error} For evaluation errors + * + * @description Internal helper function for recursive evaluation that + * always uses the global scope. This function is used to avoid circular + * dependencies and infinite recursion when evaluating nested expressions + * that need access to the global scope. + * + * This function duplicates the logic of evalNode but without the scope + * parameter, ensuring that all variable lookups go through the global scope. + * It's primarily used for evaluating function bodies and other expressions + * that need to be isolated from local scope contexts. + * + * The function also implements the forward declaration pattern for recursive + * functions, maintaining consistency with the other evaluation functions. + */ + const localEvalNode = (node) => { + callStackTracker.push('localEvalNode', node?.type || 'unknown'); + + try { + if (!node) { + return undefined; + } + switch (node.type) { + case 'NumberLiteral': + return parseFloat(node.value); + case 'StringLiteral': + return node.value; + case 'BooleanLiteral': + return node.value; + case 'PlusExpression': + return localEvalNode(node.left) + localEvalNode(node.right); + case 'MinusExpression': + return localEvalNode(node.left) - localEvalNode(node.right); + case 'MultiplyExpression': + return localEvalNode(node.left) * localEvalNode(node.right); + case 'DivideExpression': + const divisor = localEvalNode(node.right); + if (divisor === 0) { + throw new Error('Division by zero'); + } + return localEvalNode(node.left) / localEvalNode(node.right); + case 'ModuloExpression': + return localEvalNode(node.left) % localEvalNode(node.right); + case 'PowerExpression': + return Math.pow(localEvalNode(node.left), localEvalNode(node.right)); + case 'EqualsExpression': + return localEvalNode(node.left) === localEvalNode(node.right); + case 'LessThanExpression': + return localEvalNode(node.left) < localEvalNode(node.right); + case 'GreaterThanExpression': + return localEvalNode(node.left) > localEvalNode(node.right); + case 'LessEqualExpression': + return localEvalNode(node.left) <= localEvalNode(node.right); + case 'GreaterEqualExpression': + return localEvalNode(node.left) >= localEvalNode(node.right); + case 'NotEqualExpression': + return localEvalNode(node.left) !== localEvalNode(node.right); + case 'AndExpression': + return !!(localEvalNode(node.left) && localEvalNode(node.right)); + case 'OrExpression': + return !!(localEvalNode(node.left) || localEvalNode(node.right)); + case 'XorExpression': + const leftVal = localEvalNode(node.left); + const rightVal = localEvalNode(node.right); + return !!((leftVal && !rightVal) || (!leftVal && rightVal)); + case 'NotExpression': + return !localEvalNode(node.operand); + case 'UnaryMinusExpression': + return -localEvalNode(node.operand); + case 'TableLiteral': + const table = {}; + let arrayIndex = 1; + + for (const entry of node.entries) { + if (entry.key === null) { + // Array-like entry: {1, 2, 3} + table[arrayIndex] = localEvalNode(entry.value); + arrayIndex++; + } else { + // Key-value entry: {name: "Alice", age: 30} + let key; + if (entry.key.type === 'Identifier') { + // Convert identifier keys to strings + key = entry.key.value; + } else { + // For other key types (numbers, strings), evaluate normally + key = localEvalNode(entry.key); + } + const value = localEvalNode(entry.value); + table[key] = value; + } + } + + return table; + case 'TableAccess': + const tableValue = localEvalNode(node.table); + let keyValue; + + // Handle different key types + if (node.key.type === 'Identifier') { + // For dot notation, use the identifier name as the key + keyValue = node.key.value; + } else { + // For bracket notation, evaluate the key expression + keyValue = localEvalNode(node.key); + } + + if (typeof tableValue !== 'object' || tableValue === null) { + throw new Error('Cannot access property of non-table value'); + } + + if (tableValue[keyValue] === undefined) { + throw new Error(`Key '${keyValue}' not found in table`); + } + + return tableValue[keyValue]; + case 'AssignmentExpression': + // Prevent reassignment of standard library functions + if (globalScope.hasOwnProperty(node.name)) { + throw new Error(`Cannot reassign immutable variable: ${node.name}`); + } + + // Check if this is a function assignment for potential recursion + if (node.value.type === 'FunctionDefinition' || node.value.type === 'FunctionDeclaration') { + // Create a placeholder function that will be replaced + let placeholder = function(...args) { + // This should never be called, but if it is, it means we have a bug + throw new Error(`Function ${node.name} is not yet fully defined`); + }; + + // Store the placeholder in global scope + globalScope[node.name] = placeholder; + + // Now evaluate the function definition with access to the placeholder + const actualFunction = localEvalNode(node.value); + + // Replace the placeholder with the actual function + globalScope[node.name] = actualFunction; + return; + } + + globalScope[node.name] = localEvalNode(node.value); + return; + case 'Identifier': + const identifierValue = globalScope[node.value]; + if (identifierValue === undefined && node.value) { + return node.value; + } + return identifierValue; + case 'FunctionDeclaration': + // For anonymous functions, the name comes from the assignment + // The function itself doesn't have a name, so we just return + // The assignment will handle storing it in the global scope + return function(...args) { + callStackTracker.push('FunctionCall', node.params.join(',')); + try { + let nestedScope = Object.create(globalScope); + for (let i = 0; i < node.params.length; i++) { + nestedScope[node.params[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, nestedScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionDefinition': + // Create a function from the function definition + return function(...args) { + callStackTracker.push('FunctionCall', node.parameters.join(',')); + try { + let nestedScope = Object.create(globalScope); + for (let i = 0; i < node.parameters.length; i++) { + nestedScope[node.parameters[i]] = args[i]; + } + return localEvalNodeWithScope(node.body, nestedScope); + } finally { + callStackTracker.pop(); + } + }; + case 'FunctionCall': + let localFunc; + if (typeof node.name === 'string') { + // Regular function call with string name + localFunc = globalScope[node.name]; + } else if (node.name.type === 'Identifier') { + // Function call with identifier + localFunc = globalScope[node.name.value]; + } else { + // Function call from expression (e.g., parenthesized function, higher-order) + localFunc = localEvalNode(node.name); + } + + if (localFunc instanceof Function) { + let args = node.args.map(localEvalNode); + return localFunc(...args); + } + throw new Error(`Function is not defined or is not callable`); + case 'WhenExpression': + // Handle both single values and arrays of values + const whenValues = Array.isArray(node.value) + ? node.value.map(localEvalNode) + : [localEvalNode(node.value)]; + + for (const caseItem of node.cases) { + // Handle both single patterns and arrays of patterns + const patterns = caseItem.pattern.map(localEvalNode); + + // Check if patterns match the values + let matches = true; + if (whenValues.length !== patterns.length) { + matches = false; + } else { + for (let i = 0; i < whenValues.length; i++) { + const value = whenValues[i]; + const pattern = patterns[i]; + + if (pattern === true) { // Wildcard pattern + // Wildcard always matches + continue; + } else if (value !== pattern) { + matches = false; + break; + } + } + } + + if (matches) { + const results = caseItem.result.map(localEvalNode); + if (results.length === 1) { + return results[0]; + } + return results.join(' '); + } + } + throw new Error('No matching pattern found'); + case 'WildcardPattern': + return true; + case 'IOInExpression': + const readline = require('readline'); + const rl = readline.createInterface({ + input: process.stdin, + output: process.stdout + }); + + return new Promise((resolve) => { + rl.question('', (input) => { + rl.close(); + const num = parseInt(input); + resolve(isNaN(num) ? input : num); + }); + }); + case 'IOOutExpression': + const localOutputValue = localEvalNode(node.value); + console.log(localOutputValue); + return localOutputValue; + case 'IOAssertExpression': + const localAssertionValue = localEvalNode(node.value); + if (!localAssertionValue) { + throw new Error('Assertion failed'); + } + return localAssertionValue; + case 'FunctionReference': + const localFunctionValue = globalScope[node.name]; + if (localFunctionValue === undefined) { + throw new Error(`Function ${node.name} is not defined`); + } + if (typeof localFunctionValue !== 'function') { + throw new Error(`${node.name} is not a function`); + } + return localFunctionValue; + case 'ArrowExpression': + // Arrow expressions are function bodies that should be evaluated + return localEvalNode(node.body); + default: + throw new Error(`Unknown node type: ${node.type}`); } - current++; // Skip right paren - return node; + } finally { + callStackTracker.pop(); } + }; - if (token.type === TokenType.SEMICOLON) { - current++; - return; + let lastResult; + for (let node of ast.body) { + if (node) { + lastResult = evalNode(node); } + } + + if (lastResult instanceof Promise) { + return lastResult.then(result => { + return result; + }); + } + + return lastResult; +} - throw new TypeError(token.type); +/** + * Debug logging utility function. + * + * @param {string} message - Debug message to log + * @param {*} [data=null] - Optional data to log with the message + * + * @description Logs debug messages to console when DEBUG environment variable is set. + * Provides verbose output during development while remaining silent in production. + * + * Debug functions are gated by the DEBUG environment variable, allowing for + * verbose output during development and silent operation in production. This + * approach makes it easy to trace execution and diagnose issues without + * cluttering normal output. + */ +function debugLog(message, data = null) { + if (process.env.DEBUG) { + console.log(`[DEBUG] ${message}`); + if (data) { + console.log(data); + } } +} - let ast = { - type: 'Program', - body: [], - }; +/** + * Debug error logging utility function. + * + * @param {string} message - Debug error message to log + * @param {Error} [error=null] - Optional error object to log + * + * @description Logs debug error messages to console when DEBUG environment variable is set. + * Provides verbose error output during development while remaining silent in production. + * + * Debug functions are gated by the DEBUG environment variable, allowing for + * verbose output during development and silent operation in production. This + * approach makes it easy to trace execution and diagnose issues without + * cluttering normal output. + */ +function debugError(message, error = null) { + if (process.env.DEBUG) { + console.error(`[DEBUG ERROR] ${message}`); + if (error) { + console.error(error); + } + } +} - while (current < tokens.length) { - const node = walk(); - if (node !== null) { - ast.body.push(node); +/** + * Call stack tracking for debugging recursion issues. + * + * @description Tracks function calls to help identify infinite recursion + * and deep call stacks that cause stack overflow errors. This is essential + * for debugging the interpreter's recursive evaluation of AST nodes. + * + * The tracker maintains a stack of function calls with timestamps and context + * information, counts function calls to identify hot paths, and detects + * potential infinite recursion by monitoring stack depth. + * + * This tool is particularly important for the combinator-based architecture + * where function calls are the primary execution mechanism, and complex + * nested expressions can lead to deep call stacks. + */ +const callStackTracker = { + stack: [], + maxDepth: 0, + callCounts: new Map(), + + /** + * Push a function call onto the stack + * @param {string} functionName - Name of the function being called + * @param {string} context - Context where the call is happening + */ + push: function(functionName, context = '') { + const callInfo = { functionName, context, timestamp: Date.now() }; + this.stack.push(callInfo); + + // Track maximum depth + if (this.stack.length > this.maxDepth) { + this.maxDepth = this.stack.length; + } + + // Count function calls + const key = `${functionName}${context ? `:${context}` : ''}`; + this.callCounts.set(key, (this.callCounts.get(key) || 0) + 1); + + // Check for potential infinite recursion + if (this.stack.length > 1000) { + console.error('=== POTENTIAL INFINITE RECURSION DETECTED ==='); + console.error('Call stack depth:', this.stack.length); + console.error('Function call counts:', Object.fromEntries(this.callCounts)); + console.error('Recent call stack:'); + this.stack.slice(-10).forEach((call, i) => { + console.error(` ${this.stack.length - 10 + i}: ${call.functionName}${call.context ? ` (${call.context})` : ''}`); + }); + throw new Error(`Potential infinite recursion detected. Call stack depth: ${this.stack.length}`); + } + + if (process.env.DEBUG && this.stack.length % 100 === 0) { + console.log(`[DEBUG] Call stack depth: ${this.stack.length}, Max: ${this.maxDepth}`); } + }, + + /** + * Pop a function call from the stack + */ + pop: function() { + return this.stack.pop(); + }, + + /** + * Get current stack depth + */ + getDepth: function() { + return this.stack.length; + }, + + /** + * Get call statistics + */ + getStats: function() { + return { + currentDepth: this.stack.length, + maxDepth: this.maxDepth, + callCounts: Object.fromEntries(this.callCounts) + }; + }, + + /** + * Reset the tracker + */ + reset: function() { + this.stack = []; + this.maxDepth = 0; + this.callCounts.clear(); } +}; - return ast; +/** + * Cross-platform file I/O utility + * + * @param {string} filePath - Path to the file to read + * @returns {Promise<string>} File contents as a string + * @throws {Error} For file reading errors + * + * @description Handles file reading across different platforms (Node.js, Bun, browser) + * with appropriate fallbacks for each environment. This function is essential for + * the language's file execution model where scripts are loaded from .txt files. + * + * The function prioritizes ES modules compatibility by using dynamic import, + * but falls back to require for older Node.js versions. Browser environments + * are not supported for file I/O operations. + * + * This cross-platform approach ensures the language can run in various JavaScript + * environments while maintaining consistent behavior. + */ +async function readFile(filePath) { + // Check if we're in a browser environment + if (typeof window !== 'undefined') { + // Browser environment - would need to implement file input or fetch + throw new Error('File I/O not supported in browser environment'); + } + + // Node.js or Bun environment + try { + // Try dynamic import for ES modules compatibility + const fs = await import('fs'); + return fs.readFileSync(filePath, 'utf8'); + } catch (error) { + // Fallback to require for older Node.js versions + const fs = require('fs'); + return fs.readFileSync(filePath, 'utf8'); + } } -// Interpreter -function interpreter(ast) { - let globalScope = {}; - - function evalNode(node) { - switch (node.type) { - case 'NumberLiteral': - return parseInt(node.value); - case 'PlusExpression': - return evalNode(node.left) + evalNode(node.right); - case 'AssignmentExpression': - globalScope[node.name] = evalNode(node.value); - return; - case 'Identifier': - return globalScope[node.value]; - case 'IfExpression': - return evalNode(node.test) ? evalNode(node.consequent) : node.alternate ? evalNode(node.alternate) : undefined; - case 'FunctionDeclaration': - globalScope[node.name] = function() { - let localScope = Object.create(globalScope); - for (let i = 0; i < node.params.length; i++) { - localScope[node.params[i]] = arguments[i]; - } - let lastResult; - for (let bodyNode of node.body) { - lastResult = evalNode(bodyNode); - } - return lastResult; - }; - return; - case 'FunctionCall': - if (globalScope[node.name] instanceof Function) { - let args = node.args.map(evalNode); - return globalScope[node.name].apply(null, args); +/** + * Reads a file, tokenizes, parses, and interprets it. + * + * @param {string} filePath - Path to the file to execute + * @returns {Promise<*>} The result of executing the file + * @throws {Error} For file reading, parsing, or execution errors + * + * @description Main entry point for file execution. Handles the complete language + * pipeline: file reading, lexical analysis, parsing, and interpretation. + * + * This function orchestrates the entire language execution process: + * 1. Reads the source file using cross-platform I/O utilities + * 2. Tokenizes the source code using the lexer + * 3. Parses tokens into an AST using the combinator-based parser + * 4. Interprets the AST using the combinator-based interpreter + * + * The function provides comprehensive error handling and debug output at each + * stage for transparency and troubleshooting. It also manages the call stack + * tracker to provide execution statistics and detect potential issues. + * + * Supports both synchronous and asynchronous execution, with proper + * error handling and process exit codes. + */ +async function executeFile(filePath) { + try { + // Validate file extension + if (!filePath.endsWith('.txt')) { + throw new Error('Only .txt files are supported'); + } + + const input = await readFile(filePath); + + debugLog('Input:', input); + + const tokens = lexer(input); + debugLog('Tokens:', tokens); + + const ast = parser(tokens); + debugLog('AST:', JSON.stringify(ast, null, 2)); + + const result = interpreter(ast); + + if (result instanceof Promise) { + result.then(finalResult => { + if (finalResult !== undefined) { + console.log(finalResult); } - throw new Error(`Function ${node.name} is not defined`); - default: - throw new Error(`Unknown node type: ${node.type}`); + // Print call stack statistics after execution + const stats = callStackTracker.getStats(); + console.log('\n=== CALL STACK STATISTICS ==='); + console.log('Maximum call stack depth:', stats.maxDepth); + console.log('Function call counts:', JSON.stringify(stats.callCounts, null, 2)); + }).catch(error => { + console.error(`Error executing file: ${error.message}`); + // Print call stack statistics on error + const stats = callStackTracker.getStats(); + console.error('\n=== CALL STACK STATISTICS ON ERROR ==='); + console.error('Maximum call stack depth:', stats.maxDepth); + console.error('Function call counts:', JSON.stringify(stats.callCounts, null, 2)); + process.exit(1); + }); + } else { + if (result !== undefined) { + console.log(result); + } + // Print call stack statistics after execution + const stats = callStackTracker.getStats(); + console.log('\n=== CALL STACK STATISTICS ==='); + console.log('Maximum call stack depth:', stats.maxDepth); + console.log('Function call counts:', JSON.stringify(stats.callCounts, null, 2)); } + } catch (error) { + console.error(`Error executing file: ${error.message}`); + // Print call stack statistics on error + const stats = callStackTracker.getStats(); + console.error('\n=== CALL STACK STATISTICS ON ERROR ==='); + console.error('Maximum call stack depth:', stats.maxDepth); + console.error('Function call counts:', JSON.stringify(stats.callCounts, null, 2)); + process.exit(1); } - - return evalNode(ast.body[0]); } -// Usage -// const tokens = lexer('2 + 2'); -// const ast = parser(tokens); -// const result = interpreter(ast); -// console.log(result); // 4 - -// const tokens2 = lexer('x : 2 + 2'); -// const ast2 = parser(tokens2); -// const result2 = interpreter(ast2); -// console.log(result2); - -const fs = require('fs'); +/** + * CLI argument handling and program entry point. + * + * @description Processes command line arguments and executes the specified file. + * Provides helpful error messages for incorrect usage. + * + * The language is designed for file execution only (no REPL), so the CLI + * enforces this usage and provides helpful error messages for incorrect invocation. + * The function validates that exactly one file path is provided and that the + * file has the correct .txt extension. + * + * Exits with appropriate error codes for different failure scenarios. + */ +async function main() { + const args = process.argv.slice(2); -// Read the input from a file -const input = fs.readFileSync('input.txt', 'utf-8'); + if (args.length === 0) { + console.error('Usage: node lang.js <file>'); + console.error(' Provide a file path to execute'); + process.exit(1); + } else if (args.length === 1) { + // Execute the file + const filePath = args[0]; + await executeFile(filePath); + } else { + // Too many arguments + console.error('Usage: node lang.js <file>'); + console.error(' Provide exactly one file path to execute'); + process.exit(1); + } +} -// Usage -const tokens = lexer(input); -const ast = parser(tokens); -const result = interpreter(ast); -console.log(result); \ No newline at end of file +// Start the program +main().catch(error => { + console.error('Fatal error:', error.message); + process.exit(1); +}); \ No newline at end of file |