petcarescript/src/interpreter/environment.js

PetCareScript - A modern, expressive programming language designed for humans

/**
 * PetCareScript Environment
 * Manages variable scope
 */

class Environment {
    constructor(enclosing = null) {
        this.enclosing = enclosing;
        this.values = new Map();
    }

    define(name, value) {
        const varName = this.extractName(name);
        this.values.set(varName, value);
    }

    ancestor(distance) {
        let environment = this;
        for (let i = 0; i < distance; i++) {
            if (!environment.enclosing) {
                throw new Error(`Cannot find ancestor at distance ${distance}`);
            }
            environment = environment.enclosing;
        }
        return environment;
    }

    getAt(distance, name) {
        const varName = this.extractName(name);
        return this.ancestor(distance).values.get(varName);
    }

    assignAt(distance, name, value) {
        const varName = this.extractName(name);
        this.ancestor(distance).values.set(varName, value);
    }

    get(name) {
        const varName = this.extractName(name);
        
        if (this.values.has(varName)) {
            return this.values.get(varName);
        }

        if (this.enclosing !== null) {
            return this.enclosing.get(varName);
        }

        throw new Error(`Undefined variable '${varName}'.`);
    }

    assign(name, value) {
        const varName = this.extractName(name);
        
        if (this.values.has(varName)) {
            this.values.set(varName, value);
            return;
        }

        if (this.enclosing !== null) {
            this.enclosing.assign(varName, value);
            return;
        }

        throw new Error(`Undefined variable '${varName}'.`);
    }

    // Helper method to extract name from various token/node formats
    extractName(name) {
        if (typeof name === 'string') {
            return name;
        }
        if (name && name.lexeme) {
            return name.lexeme;
        }
        if (name && name.name && name.name.lexeme) {
            return name.name.lexeme;
        }
        if (name && name.name) {
            return name.name;
        }
        throw new Error(`Cannot extract name from: ${JSON.stringify(name)}`);
    }

    // Debug method to see all variables in current scope
    getVariables() {
        return Array.from(this.values.keys());
    }

    // Check if variable exists in current scope (not ancestors)
    hasLocal(name) {
        const varName = this.extractName(name);
        return this.values.has(varName);
    }

    // Check if variable exists in any scope
    has(name) {
        const varName = this.extractName(name);
        
        if (this.values.has(varName)) {
            return true;
        }

        if (this.enclosing !== null) {
            return this.enclosing.has(varName);
        }

        return false;
    }
}

module.exports = Environment;