jashkenas--coffeescript/lib/coffeescript/scope.js

// Generated by CoffeeScript 2.0.0
(function() {
  // The **Scope** class regulates lexical scoping within CoffeeScript. As you
  // generate code, you create a tree of scopes in the same shape as the nested
  // function bodies. Each scope knows about the variables declared within it,
  // and has a reference to its parent enclosing scope. In this way, we know which
  // variables are new and need to be declared with `var`, and which are shared
  // with external scopes.
  var Scope,
    indexOf = [].indexOf;

  exports.Scope = Scope = class Scope {
    // Initialize a scope with its parent, for lookups up the chain,
    // as well as a reference to the **Block** node it belongs to, which is
    // where it should declare its variables, a reference to the function that
    // it belongs to, and a list of variables referenced in the source code
    // and therefore should be avoided when generating variables.
    constructor(parent, expressions, method, referencedVars) {
      var ref, ref1;
      this.parent = parent;
      this.expressions = expressions;
      this.method = method;
      this.referencedVars = referencedVars;
      this.variables = [
        {
          name: 'arguments',
          type: 'arguments'
        }
      ];
      this.positions = {};
      if (!this.parent) {
        this.utilities = {};
      }
      // The `@root` is the top-level **Scope** object for a given file.
      this.root = (ref = (ref1 = this.parent) != null ? ref1.root : void 0) != null ? ref : this;
    }

    // Adds a new variable or overrides an existing one.
    add(name, type, immediate) {
      if (this.shared && !immediate) {
        return this.parent.add(name, type, immediate);
      }
      if (Object.prototype.hasOwnProperty.call(this.positions, name)) {
        return this.variables[this.positions[name]].type = type;
      } else {
        return this.positions[name] = this.variables.push({name, type}) - 1;
      }
    }

    // When `super` is called, we need to find the name of the current method we're
    // in, so that we know how to invoke the same method of the parent class. This
    // can get complicated if super is being called from an inner function.
    // `namedMethod` will walk up the scope tree until it either finds the first
    // function object that has a name filled in, or bottoms out.
    namedMethod() {
      var ref;
      if (((ref = this.method) != null ? ref.name : void 0) || !this.parent) {
        return this.method;
      }
      return this.parent.namedMethod();
    }

    // Look up a variable name in lexical scope, and declare it if it does not
    // already exist.
    find(name, type = 'var') {
      if (this.check(name)) {
        return true;
      }
      this.add(name, type);
      return false;
    }

    // Reserve a variable name as originating from a function parameter for this
    // scope. No `var` required for internal references.
    parameter(name) {
      if (this.shared && this.parent.check(name, true)) {
        return;
      }
      return this.add(name, 'param');
    }

    // Just check to see if a variable has already been declared, without reserving,
    // walks up to the root scope.
    check(name) {
      var ref;
      return !!(this.type(name) || ((ref = this.parent) != null ? ref.check(name) : void 0));
    }

    // Generate a temporary variable name at the given index.
    temporary(name, index, single = false) {
      var diff, endCode, letter, newCode, num, startCode;
      if (single) {
        startCode = name.charCodeAt(0);
        endCode = 'z'.charCodeAt(0);
        diff = endCode - startCode;
        newCode = startCode + index % (diff + 1);
        letter = String.fromCharCode(newCode);
        num = Math.floor(index / (diff + 1));
        return `${letter}${num || ''}`;
      } else {
        return `${name}${index || ''}`;
      }
    }

    // Gets the type of a variable.
    type(name) {
      var i, len, ref, v;
      ref = this.variables;
      for (i = 0, len = ref.length; i < len; i++) {
        v = ref[i];
        if (v.name === name) {
          return v.type;
        }
      }
      return null;
    }

    // If we need to store an intermediate result, find an available name for a
    // compiler-generated variable. `_var`, `_var2`, and so on...
    freeVariable(name, options = {}) {
      var index, ref, temp;
      index = 0;
      while (true) {
        temp = this.temporary(name, index, options.single);
        if (!(this.check(temp) || indexOf.call(this.root.referencedVars, temp) >= 0)) {
          break;
        }
        index++;
      }
      if ((ref = options.reserve) != null ? ref : true) {
        this.add(temp, 'var', true);
      }
      return temp;
    }

    // Ensure that an assignment is made at the top of this scope
    // (or at the top-level scope, if requested).
    assign(name, value) {
      this.add(name, {
        value,
        assigned: true
      }, true);
      return this.hasAssignments = true;
    }

    // Does this scope have any declared variables?
    hasDeclarations() {
      return !!this.declaredVariables().length;
    }

    // Return the list of variables first declared in this scope.
    declaredVariables() {
      var v;
      return ((function() {
        var i, len, ref, results;
        ref = this.variables;
        results = [];
        for (i = 0, len = ref.length; i < len; i++) {
          v = ref[i];
          if (v.type === 'var') {
            results.push(v.name);
          }
        }
        return results;
      }).call(this)).sort();
    }

    // Return the list of assignments that are supposed to be made at the top
    // of this scope.
    assignedVariables() {
      var i, len, ref, results, v;
      ref = this.variables;
      results = [];
      for (i = 0, len = ref.length; i < len; i++) {
        v = ref[i];
        if (v.type.assigned) {
          results.push(`${v.name} = ${v.type.value}`);
        }
      }
      return results;
    }

  };

}).call(this);