simple interpreter

src/interpreter/builtin_signatures.ts

@@ -0,0 +1,106 @@
+import { BadArgumentError } from '@/utils';
+import type { DenotableValueType } from '.';
+
+export type Signature = Array<Array<DenotableValueType | Signature>>;
+
+export const primitiveOperationSignatures: Record<string, Signature> = {
+  '+': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'real'],
+    ['int', 'real', 'real'],
+    ['real', 'int', 'real'],
+  ],
+  '-': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'real'],
+    ['int', 'real', 'real'],
+    ['real', 'int', 'real'],
+  ],
+  '*': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'real'],
+    ['int', 'real', 'real'],
+    ['real', 'int', 'real'],
+  ],
+  '/': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'real'],
+    ['int', 'real', 'real'],
+    ['real', 'int', 'real'],
+  ],
+  '%': [['int', 'int', 'int']],
+  '**': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'real'],
+    ['int', 'real', 'real'],
+    ['real', 'int', 'real'],
+  ],
+  '>>': [['int', 'int', 'int']],
+  '<<': [['int', 'int', 'int']],
+  '&': [['int', 'int', 'int']],
+  '|': [['int', 'int', 'int']],
+  '^': [['int', 'int', 'int']],
+  '==': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+    ['string', 'string', 'int'],
+  ],
+  '!=': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+    ['string', 'string', 'int'],
+  ],
+  '<': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+  ],
+  '>': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+  ],
+  '<=': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+  ],
+  '>=': [
+    ['int', 'int', 'int'],
+    ['real', 'real', 'int'],
+  ],
+  '&&': [['int', 'int', 'int']],
+  '||': [['int', 'int', 'int']],
+  '!': [['int', 'int']],
+};
+
+export const getResultingType = (
+  opr: string,
+  types: DenotableValueType[],
+): DenotableValueType | Signature => {
+  const signature = primitiveOperationSignatures[opr];
+  if (!signature) {
+    throw new BadArgumentError(`Invalid operation: ${opr}`);
+  }
+
+  const resultingType = signature.find(sig => {
+    if (sig.length !== types.length) {
+      return false;
+    }
+
+    return sig.every((type, i) => {
+      if (Array.isArray(type)) {
+        return getResultingType(
+          opr,
+          types.map((t, j) => (i === j ? t : 'int')),
+        );
+      }
+      return type === 'int' || type === types[i];
+    });
+  });
+
+  if (!resultingType) {
+    throw new TypeError(
+      `Invalid types for operation ${opr}: ${types.join(', ')}`,
+    );
+  }
+
+  return resultingType as DenotableValueType | Signature;
+};

src/interpreter/environment.ts

@@ -0,0 +1,44 @@
+import { UnknownSymbolError } from '@/utils';
+import type { DenotableValue } from '.';
+
+export class Environment {
+  private scope: Map<string, DenotableValue>;
+  private parent: Environment | null;
+
+  constructor(parent: Environment | null = null) {
+    this.parent = parent;
+    this.scope = new Map();
+  }
+
+  public set(name: string, value: DenotableValue) {
+    this.scope.set(name, value);
+  }
+
+  public get(name: string): DenotableValue {
+    if (this.scope.has(name)) {
+      return this.scope.get(name);
+    }
+
+    if (this.parent) {
+      return this.parent.get(name);
+    }
+
+    throw new UnknownSymbolError(`Undefined variable: ${name}`);
+  }
+
+  public has(name: string): boolean {
+    if (this.scope.has(name)) {
+      return true;
+    }
+
+    if (this.parent) {
+      return this.parent.has(name);
+    }
+
+    return false;
+  }
+
+  public createChild(): Environment {
+    return new Environment(this);
+  }
+}

src/interpreter/index.ts

@@ -1 +1,11 @@
-export const evaluate = async (ast: Program) => {};
+export type DenotableValueType =
+  | 'null'
+  | 'int'
+  | 'real'
+  | 'string'
+  | 'function'
+  | 'reference';
+export type DenotableValue = { type: DenotableValueType; value: any };
+
+export * from './environment';
+export * from './interpreter';

src/interpreter/interpreter.ts

@@ -0,0 +1,160 @@
+import {
+  type ContinuationExpression,
+  type PrimitiveOperationExpression,
+  type Program,
+  type Value,
+} from '@/parser';
+import { Environment, type DenotableValue } from '.';
+import {
+  BadArgumentError,
+  InvalidStateError,
+  NotImplementedError,
+  type TracingLogger,
+} from '@/utils';
+
+const evaluateValue = (
+  value: Value,
+  env: Environment,
+  logger: TracingLogger,
+): DenotableValue => {
+  if (typeof value === 'string') {
+    return { type: 'string', value };
+  }
+
+  if ('real' in value) {
+    return { type: 'real', value: value.real };
+  }
+  if ('int' in value) {
+    return { type: 'int', value: value.int };
+  }
+  if ('name' in value) {
+    logger.debug(`Evaluating variable: ${value.name}`);
+    return env.get(value.name);
+  }
+
+  throw new InvalidStateError(`Invalid value: ${value}`);
+};
+
+const evaluatePrimitiveOperation = (
+  { primitiveOperation }: PrimitiveOperationExpression,
+  env: Environment,
+  logger: TracingLogger,
+) => {
+  const { opr, operands, resultBindings, continuations } = primitiveOperation;
+  if (operands.length !== 2) {
+    throw new BadArgumentError('Primitive operations must have 2 operands');
+  }
+
+  const operandValues = operands.map(operand =>
+    evaluateValue(operand, env, logger.createChild('evaluteValue')),
+  );
+
+  const rightReducingOperations = {
+    '+': (acc: number, operand: { value: number }) => acc + operand.value,
+    '-': (acc: number, operand: { value: number }) => acc - operand.value,
+    '*': (acc: number, operand: { value: number }) => acc * operand.value,
+  };
+  const leftReducingOperations = {
+    '/': (acc: number, operand: { value: number }) => acc / operand.value,
+    '%': (acc: number, operand: { value: number }) => acc % operand.value,
+    '**': (acc: number, operand: { value: number }) => acc ** operand.value,
+    '>>': (acc: number, operand: { value: number }) => acc >> operand.value,
+    '<<': (acc: number, operand: { value: number }) => acc << operand.value,
+    '&': (acc: number, operand: { value: number }) => acc & operand.value,
+    '|': (acc: number, operand: { value: number }) => acc | operand.value,
+    '^': (acc: number, operand: { value: number }) => acc ^ operand.value,
+  };
+  const someNumberIsReal = operandValues.some(({ type }) => type === 'real');
+
+  let result: DenotableValue = { type: 'null', value: null };
+  const continuationEnvironment = env.createChild();
+  if (opr in rightReducingOperations) {
+    logger.debug('Evaluating right reducing operation: ' + opr);
+    const sum = operandValues.reduce(
+      rightReducingOperations[opr as keyof typeof rightReducingOperations],
+      0,
+    );
+    result = { type: someNumberIsReal ? 'real' : 'int', value: sum };
+
+    for (const binding of resultBindings) {
+      continuationEnvironment.set(binding.name, result);
+    }
+  }
+  if (opr in leftReducingOperations) {
+    logger.debug('Evaluating left reducing operation: ' + opr);
+    const [first, ...rest] = operandValues;
+    const sum = rest.reduce(
+      leftReducingOperations[opr as keyof typeof leftReducingOperations],
+      first.value,
+    );
+    result = { type: someNumberIsReal ? 'real' : 'int', value: sum };
+
+    for (const binding of resultBindings) {
+      continuationEnvironment.set(binding.name, result);
+    }
+  }
+
+  // return the result of the last continuation
+  return continuations.reduce((_, continuation, i) => {
+    const childLogger = logger.createChild(`continuation[${i}]`);
+    return evaluteContinuationExpression(
+      continuation,
+      continuationEnvironment,
+      childLogger,
+    );
+  }, result);
+};
+
+const evaluteContinuationExpression = (
+  expr: ContinuationExpression,
+  env: Environment,
+  logger: TracingLogger,
+): DenotableValue => {
+  if ('primitiveOperation' in expr) {
+    logger.debug('Evaluating primitive operation');
+    return evaluatePrimitiveOperation(
+      expr,
+      env,
+      logger.createChild('evaluatePrimitiveOperation'),
+    );
+  }
+
+  if ('record' in expr) {
+    throw new NotImplementedError('Continuation records are not supported yet');
+  }
+  if ('select' in expr) {
+    throw new NotImplementedError('Continuation select is not supported yet');
+  }
+  if ('offset' in expr) {
+    throw new NotImplementedError('Continuation offset is not supported yet');
+  }
+  if ('application' in expr) {
+    throw new NotImplementedError(
+      'Continuation application is not supported yet',
+    );
+  }
+  if ('switch' in expr) {
+    throw new NotImplementedError('Continuation switch is not supported yet');
+  }
+  if ('fix' in expr) {
+    throw new NotImplementedError('Continuation fix is not supported yet');
+  }
+
+  throw new InvalidStateError(`Invalid continuation expression: ${expr}`);
+};
+
+export const evaluate = async (
+  ast: Program,
+  logger: TracingLogger,
+): Promise<DenotableValue> => {
+  const environment = new Environment();
+
+  return ast.reduce((_, continuation, i) => {
+    const exprLogger = logger.createChild(`statement[${i}]`);
+    return evaluteContinuationExpression(
+      continuation as ContinuationExpression,
+      environment,
+      exprLogger,
+    );
+  }, null);
+};

src/parser/grammar.pegjs

@@ -285,6 +285,7 @@ ComparisonOperation
   / "!"
   / ">"
   / "<"
+  / "||"
 
 Integer = digits:("-"? [0-9]+) !"." { return { int: parseInt(digits.join(''), 10) }; }
 

src/utils/exception.ts

@@ -1 +1,9 @@
-export class NotImplementedException extends Error {}
+export class NotImplementedError extends Error {}
+
+export class UnknownSymbolError extends Error {}
+
+export class InvalidStateError extends Error {}
+
+export class BadArgumentError extends Error {}
+
+export class TypeError extends Error {}

test/interpreter.spec.ts

@@ -0,0 +1,12 @@
+import { expect, test } from 'bun:test';
+import { TestPrograms } from './programs';
+import { peggyParse } from '@/parser';
+import { evaluate } from '@/interpreter';
+import { testingLogger } from './logger';
+
+test('Add (1 real) and (3 int) => (4 real)', async () => {
+  const ast = peggyParse(await TestPrograms.AddOneThree);
+
+  const result = await evaluate(ast, testingLogger);
+  expect(result).toEqual({ type: 'real', value: 4 });
+});

test/parser.spec.ts

@@ -3,5 +3,13 @@ import { TestPrograms } from './programs';
 import { peggyParse } from '@/parser';
 
 test('Primitive Operations', async () => {
-  const ast = peggyParse(await TestPrograms.AddOneThree);
+  const [operation] = peggyParse(await TestPrograms.AddOneThree);
+  const { primitiveOperation } = operation;
+
+  expect(primitiveOperation).toEqual({
+    opr: '+',
+    operands: [{ real: 1 }, { int: 3 }],
+    resultBindings: [{ name: 'result' }],
+    continuations: [],
+  });
 });

test/programs/add-1-3.cps

@@ -1,2 +1 @@
-PRIMOP(+, [INT 1, INT 2], [u],
-  [APP(LABEL identity, [VAR u])])
+PRIMOP(+, [REAL 1, INT 3], [result], [])