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Resolving Symbolic References in a CodeDOM (Part 7)

, 2 Dec 2012 CDDL
Resolving symbolic references in a CodeDOM.
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Base
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Base
Conditionals
Base
Messages
Base
Pragmas
Base
Symbols
Base
Base
Expressions
AnonymousMethods
Base
Operators
Base
Binary
Arithmetic
Base
Assignment
Base
Bitwise
Base
Conditional
Relational
Base
Shift
Base
Other
Base
Unary
Base
Other
References
Base
GotoTargets
Base
Methods
Namespaces
Other
Properties
Types
Base
Variables
Base
Projects
Namespaces
References
Base
Statements
Base
Conditionals
Base
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Constraints
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Base
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Utilties
// The Nova Project by Ken Beckett.
// Copyright (C) 2007-2012 Inevitable Software, all rights reserved.
// Released under the Common Development and Distribution License, CDDL-1.0: http://opensource.org/licenses/cddl1.php

using Nova.Parsing;
using Nova.Rendering;
using Nova.Resolving;

namespace Nova.CodeDOM
{
    /// <summary>
    /// Imports the contents of a <see cref="Namespace"/> into the current scope.
    /// </summary>
    public class UsingDirective : Statement
    {
        #region /* FIELDS */

        /// <summary>
        /// The expression should be either a <see cref="NamespaceRef"/>, or a <see cref="Dot"/> operator whose right-most
        /// operand evaluates to a <see cref="NamespaceRef"/>.
        /// </summary>
        protected Expression _namespace;

        #endregion

        #region /* CONSTRUCTORS */

        /// <summary>
        /// Create a <see cref="UsingDirective"/>.
        /// </summary>
        public UsingDirective(Expression expression)
        {
            Namespace = expression;
        }

        #endregion

        #region /* PROPERTIES */

        /// <summary>
        /// The namespace <see cref="Expression"/>.
        /// </summary>
        public Expression Namespace
        {
            get { return _namespace; }
            set { SetField(ref _namespace, value, true); }
        }

        /// <summary>
        /// The keyword associated with the <see cref="Statement"/>.
        /// </summary>
        public override string Keyword
        {
            get { return ParseToken; }
        }

        #endregion

        #region /* METHODS */

        /// <summary>
        /// Evaluate the namespace expression into the targeted <see cref="NamespaceRef"/>.
        /// </summary>
        public NamespaceRef GetNamespaceRef()
        {
            Expression expression = _namespace.SkipPrefixes();
            return (expression is NamespaceRef ? (NamespaceRef)expression : (expression is AliasRef ? ((AliasRef)expression).Namespace : null));
        }

        /// <summary>
        /// Deep-clone the code object.
        /// </summary>
        public override CodeObject Clone()
        {
            UsingDirective clone = (UsingDirective)base.Clone();
            clone.CloneField(ref clone._namespace, _namespace);
            return clone;
        }

        #endregion

        #region /* PARSING */

        /// <summary>
        /// The token used to parse the code object.
        /// </summary>
        public const string ParseToken = "using";

        internal static void AddParsePoints()
        {
            // Use a parse-priority of 100 (Alias uses 0, Using uses 200)
            Parser.AddParsePoint(ParseToken, 100, Parse, typeof(NamespaceDecl));
        }

        /// <summary>
        /// Parse a <see cref="UsingDirective"/>.
        /// </summary>
        public static UsingDirective Parse(Parser parser, CodeObject parent, ParseFlags flags)
        {
            if (parser.PeekNextTokenText() != Expression.ParseTokenStartGroup)
                return new UsingDirective(parser, parent);
            return null;
        }

        protected UsingDirective(Parser parser, CodeObject parent)
            : base(parser, parent)
        {
            parser.NextToken();  // Move past 'using'
            SetField(ref _namespace, Expression.Parse(parser, this, true), false);
            ParseTerminator(parser);
        }

        #endregion

        #region /* RESOLVING */

        /// <summary>
        /// Resolve all child symbolic references, using the specified <see cref="ResolveCategory"/> and <see cref="ResolveFlags"/>.
        /// </summary>
        public override CodeObject Resolve(ResolveCategory resolveCategory, ResolveFlags flags)
        {
            if ((flags & (ResolveFlags.Phase2 | ResolveFlags.Phase3)) == 0)
                _namespace = (Expression)_namespace.Resolve(ResolveCategory.Namespace, flags);
            return this;
        }

        /// <summary>
        /// Returns true if the code object is an <see cref="UnresolvedRef"/> or has any <see cref="UnresolvedRef"/> children.
        /// </summary>
        public override bool HasUnresolvedRef()
        {
            if (_namespace != null && _namespace.HasUnresolvedRef())
                return true;
            return base.HasUnresolvedRef();
        }

        #endregion

        #region /* FORMATTING */

        /// <summary>
        /// True if the <see cref="Statement"/> has parens around its argument.
        /// </summary>
        public override bool HasArgumentParens
        {
            get { return false; }
        }

        /// <summary>
        /// True if the <see cref="Statement"/> has a terminator character by default.
        /// </summary>
        public override bool HasTerminatorDefault
        {
            get { return true; }
        }

        /// <summary>
        /// Determine a default of 1 or 2 newlines when adding items to a <see cref="Block"/>.
        /// </summary>
        public override int DefaultNewLines(CodeObject previous)
        {
            // Default to a preceeding blank line if the object has first-on-line annotations
            if (HasFirstOnLineAnnotations)
                return 2;

            // Default to a preceeding blank line if the previous object was another using directive
            // with a different root namespace, otherwise use a single newline.
            if (previous is UsingDirective)
            {
                SymbolicRef symbolicRef = ((UsingDirective)previous).Namespace.FirstPrefix() as SymbolicRef;
                if (symbolicRef != null && !symbolicRef.IsSameRef(Namespace.FirstPrefix() as SymbolicRef))
                    return 2;
                return 1;
            }

            // Default to no preceeding blank line if the previous object was an alias directive with
            // the same root namespace, otherwise use a preceeding blank line.
            if (previous is Alias)
            {
                SymbolicRef symbolicRef = ((Alias)previous).Expression.FirstPrefix() as SymbolicRef;
                if (symbolicRef != null && symbolicRef.IsSameRef(Namespace.FirstPrefix() as SymbolicRef))
                    return 1;
                return 2;
            }

            // Default to a preceeding blank line if the object is a different type than the previous one
            if (previous.GetType() != GetType())
                return 2;
            return 1;
        }

        /// <summary>
        /// Determines if the code object only requires a single line for display.
        /// </summary>
        public override bool IsSingleLine
        {
            get { return (base.IsSingleLine && (_namespace == null || (!_namespace.IsFirstOnLine && _namespace.IsSingleLine))); }
            set
            {
                base.IsSingleLine = value;
                if (value && _namespace != null)
                {
                    _namespace.IsFirstOnLine = false;
                    _namespace.IsSingleLine = true;
                }
            }
        }

        #endregion

        #region /* RENDERING */

        protected override void AsTextArgument(CodeWriter writer, RenderFlags flags)
        {
            if (_namespace != null)
                _namespace.AsText(writer, flags);
        }

        #endregion
    }
}

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This article, along with any associated source code and files, is licensed under The Common Development and Distribution License (CDDL)

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About the Author

KenBeckett
Software Developer (Senior)
United States United States
I've been writing software since the late 70's, currently focusing mainly on C#.NET. I also like to travel around the world, and I own a Chocolate Factory (sadly, none of my employees are oompa loompas).

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