Click here to Skip to main content
Click here to Skip to main content
Add your own
alternative version

Resolving Symbolic References in a CodeDOM (Part 7)

, 2 Dec 2012
Resolving symbolic references in a CodeDOM.
Nova.0.6.exe.zip
Nova.0.6.zip
Nova.CLI
Properties
Nova.CodeDOM
CodeDOM
Annotations
Base
Comments
Base
DocComments
CodeRef
Base
List
Name
Base
Other
Simple
CompilerDirectives
Base
Conditionals
Base
Messages
Base
Pragmas
Base
Symbols
Base
Base
Interfaces
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
Assemblies
Namespaces
References
Base
Statements
Base
Conditionals
Base
Exceptions
Generics
Constraints
Base
Iterators
Base
Jumps
Loops
Methods
OperatorDecls
Miscellaneous
Namespaces
Properties
Base
Events
Types
Base
Variables
Base
Parsing
Base
Properties
Rendering
Resolving
Utilities
Mono.Cecil
Reflection
Nova.Examples
Properties
Nova.Studio
Images
About.png
Configuration.png
EditCopy.png
EditCut.png
EditDelete.png
EditPaste.png
EditRedo.png
EditUndo.png
Error.png
Exit.png
FileNew.png
FileOpen.png
FileSave.png
FileSaveAll.png
FileSaveAs.png
Find.png
Help.png
Info.png
Logo.png
Options.png
Print.png
PrintPreview.png
Properties.png
Todo.png
Warning.png
Objects.ico
Properties
Settings.settings
Nova.Test
Properties
Nova.UI
CodeDOM
Annotations
Base
Comments
Base
DocComments
CodeRef
Base
List
Name
Base
Other
Simple
CompilerDirectives
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
Exceptions
Generics
Constraints
Base
Iterators
Base
Jumps
Loops
Methods
OperatorDecls
Miscellaneous
Namespaces
Properties
Base
Events
Types
Base
Variables
Base
Properties
Resolving
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 System;
using Mono.Cecil;

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

namespace Nova.CodeDOM
{
    /// <summary>
    /// Represents conditional flow control, and consists of a constant expression (of integral or string type)
    /// along with one or more <see cref="Case"/> or <see cref="Default"/> child statements.
    /// </summary>
    public class Switch : BlockStatement
    {
        #region /* FIELDS */

        protected Expression _target;

        #endregion

        #region /* CONSTRUCTORS */

        /// <summary>
        /// Create a <see cref="Switch"/> on the specified target <see cref="Expression"/>.
        /// </summary>
        public Switch(Expression target)
        {
            Target = target;
        }

        /// <summary>
        /// Create a <see cref="Switch"/> on the specified target <see cref="Expression"/>.
        /// </summary>
        public Switch(Expression target, params SwitchItem[] items)
            : this(target)
        {
            foreach (SwitchItem item in items)
                Add(item);
        }

        #endregion

        #region /* PROPERTIES */

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

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

        #endregion

        #region /* METHODS */

        /// <summary>
        /// Add a <see cref="SwitchItem"/>.
        /// </summary>
        public void Add(SwitchItem item)
        {
            base.Add(item);
        }

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

        #endregion

        #region /* PARSING */

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

        internal static void AddParsePoints()
        {
            Parser.AddParsePoint(ParseToken, Parse, typeof(IBlock));
        }

        /// <summary>
        /// Parse a <see cref="Switch"/>.
        /// </summary>
        public static Switch Parse(Parser parser, CodeObject parent, ParseFlags flags)
        {
            return new Switch(parser, parent);
        }

        protected Switch(Parser parser, CodeObject parent)
            : base(parser, parent)
        {
            // Parse keyword, argument, and body
            // Do NOT do any post-processing in the body parsing, because we're going to do it below
            ParseKeywordArgumentBody(parser, ref _target, false, true);

            // Do some special processing of switch items:
            for (int i = _body.Count - 1; i >= 0; --i)
            {
                CodeObject item = _body[i];
                if (item is Break || item is Return)
                {
                    // Check for Break or Return statements outside of a SwitchItem block, and move them inside
                    // the previous block (this can occur when they are outside the SwitchItem's curly braces).
                    if (i > 0)
                    {
                        CodeObject previousItem = _body[i - 1];
                        if (previousItem is SwitchItem)
                        {
                            ((SwitchItem)previousItem).Body.Add(item);
                            _body.RemoveAt(i);
                        }
                    }
                }
                else if (item is CommentBase)
                {
                    // Merge any comments into adjacent SwitchItems if appropriate
                    _body.PostProcessComment((CommentBase)item, i);
                }
                else if (item is SwitchItem)
                {
                    // Check for SwitchItems without braces where the last object in the block is a conditional
                    // directive, and move them to the parent block if they don't seem to "belong" to the child.
                    // Also, if the last object is a DocComment, move it to the parent block.
                    Block itemBody = ((SwitchItem)item).Body;
                    if (itemBody != null && !itemBody.HasBraces)
                    {
                        bool move = false;
                        CodeObject last = itemBody.Last;
                        if (last is CompilerDirective)
                        {
                            move = true;
                            if (last is EndIfDirective)
                            {
                                // Don't move the endif if there's an associated conditional in the same block
                                for (int n = itemBody.Count - 2; n >= 0; --n)
                                {
                                    CodeObject itemMember = itemBody[n];
                                    if (itemMember is ConditionalDirective)
                                    {
                                        move = false;
                                        break;
                                    }
                                }
                            }
                        }
                        else if (last is DocComment)
                            move = true;
                        if (move)
                        {
                            // Move the object up to the parent block
                            _body.Insert(i + 1, last);
                            itemBody.RemoveAt(itemBody.Count - 1);
                        }
                    }
                }
            }
        }

        #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)
        {
            _target = (Expression)_target.Resolve(ResolveCategory.Expression, flags);

            // To allow forward references by any 'goto case ...' statements, resolve the constant expressions of all
            // child Case statements before resolving the body.
            if (_body != null)
            {
                foreach (Case @case in _body.Find<Case>())
                    @case.ResolveConstantExpression(flags);
            }

            return base.Resolve(ResolveCategory.CodeObject, flags);
        }

        /// <summary>
        /// Resolve child code objects that match the specified name, moving up the tree until a complete match is found.
        /// </summary>
        public override void ResolveRefUp(string name, Resolver resolver)
        {
            // If we're on our way up the code tree from a SwitchItem (case/default), we have to search the top block
            // of any other items that preceed the one we originated from *if* those items don't have braces around
            // their top block, so that we can match any local variable declarations.
            foreach (SwitchItem switchItem in _body.Find<SwitchItem>())
            {
                // It would be nice to skip searching the origin item, but it's hardly worth the trouble.  As with
                // locals elsewhere at the same level, we will match forward references, but the analysis phase will
                // detect these and report them as errors.
                Block body = switchItem.Body;
                if (body != null && !body.HasBraces)
                    switchItem.ResolveRef(name, resolver);
            }

            if (_parent != null && !resolver.HasCompleteMatch)
                _parent.ResolveRefUp(name, resolver);
        }

        /// <summary>
        /// Resolve child code objects that match the specified name and are valid goto targets, moving up the tree until a complete match is found.
        /// </summary>
        public override void ResolveGotoTargetUp(string name, Resolver resolver)
        {
            if (name.StartsWith("case "))
            {
                // Handle a "goto case ...":
                if (_body != null)
                {
                    // Although case statements are named objects, we can't just match on their name - we need to match if there's
                    // an implicit conversion between the goto and target expressions.  Also, a case expression doesn't have to be
                    // a Literal, but can be a constant expression with a Cast or other operators.
                    Goto associatedGoto = resolver.UnresolvedRef.Parent as Goto;
                    if (associatedGoto != null)
                    {
                        TypeRef targetTypeRef = associatedGoto.ConstantExpression.EvaluateType() as TypeRef;
                        TypeRef switchTypeRef = Target.EvaluateType() as TypeRef;
                        if (targetTypeRef != null && switchTypeRef != null)
                        {
                            // Verify that the target type is implicitly convertible to the Switch type.
                            // If not, create a warning, but continue to attempt resolution of the target reference anyway.
                            associatedGoto.RemoveAllMessages(MessageSource.Resolve);
                            if (!targetTypeRef.IsImplicitlyConvertibleTo(switchTypeRef))
                            {
                                associatedGoto.AttachMessage("The 'goto case' value isn't implicitly convertible to the 'switch' type '" + switchTypeRef.AsString() + "'.",
                                    MessageSeverity.Warning, MessageSource.Resolve);
                            }
                            if (targetTypeRef.IsEnum)
                            {
                                // Handle enum types
                                foreach (Case @case in _body.Find<Case>())
                                {
                                    // Verify that the enum types are the same
                                    TypeRefBase caseConstantRef = @case.ConstantExpression.EvaluateType();
                                    if (targetTypeRef.IsSameRef(caseConstantRef))
                                    {
                                        // Verify that the enum constant values are identical using Equals().  Also, verify that they're
                                        // indeed constants (they might not be if the enum members were still UnresolvedRefs).
                                        if (targetTypeRef.IsConst && caseConstantRef.IsConst)
                                        {
                                            if (((EnumConstant)targetTypeRef.GetConstantValue()).ConstantValue.Equals(((EnumConstant)caseConstantRef.GetConstantValue()).ConstantValue))
                                                resolver.AddMatch(@case);
                                        }
                                    }
                                }
                            }
                            else
                            {
                                // Handle built-in types - convert the targetTypeRef constant to the type of the Switch.
                                Type switchType = (switchTypeRef.Reference is TypeReference ? TypeRef.GetEquivalentType((TypeReference)switchTypeRef.Reference) : switchTypeRef.Reference as Type);
                                object targetConstant = targetTypeRef.GetConstantValue();

                                // If the target constant isn't a null reference, try to convert it to the Switch type
                                bool conversionSuccessful = true;
                                if (targetConstant != null)
                                {
                                    targetConstant = TypeUtil.ChangeType(targetConstant, switchType);
                                    if (targetConstant == null)
                                        conversionSuccessful = false;
                                }
                                if (conversionSuccessful)
                                {
                                    foreach (Case @case in _body.Find<Case>())
                                    {
                                        // Get the case constant, and make sure it's also of the Switch type (it might not be)
                                        object caseConstant = @case.ConstantExpression.EvaluateType().GetConstantValue();
                                        caseConstant = TypeUtil.ChangeType(caseConstant, switchType);

                                        // Compare the target constant object to the case constant using Equals() to do a value compare instead of a reference compare
                                        bool matches = (caseConstant == null ? targetConstant == null : caseConstant.Equals(targetConstant));
                                        if (matches)
                                            resolver.AddMatch(@case);
                                    }
                                }
                            }
                        }
                    }
                }
                // The search for a "goto case ..." stops at the first enclosing Switch statement
            }
            else if (name == Default.ParseToken)
            {
                // Handle a "goto default":
                resolver.AddMatch(Find<Default>());
                // The search for a "goto default" stops at the first enclosing Switch statement
            }
            else
            {
                // Handle a "goto <label>":

                // As we're on our way up the code tree from a SwitchItem (case/default), we have to search
                // the top block of any other SwitchItems (preceeding OR following) for any labels *if* they
                // don't have braces around their top block.
                foreach (SwitchItem switchItem in Find<SwitchItem>())
                {
                    // It would be nice to skip searching the origin item, but it's hardly worth the trouble
                    Block body = switchItem.Body;
                    if (body != null && !body.HasBraces)
                        body.ResolveGotoTargetUp(name, resolver);
                }

                // If we didn't find a match, continue looking through parent scopes
                if (_parent != null && !resolver.HasCompleteMatch)
                    _parent.ResolveGotoTargetUp(name, resolver);
            }
        }

        /// <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 (_target != null && _target.HasUnresolvedRef())
                return true;
            return base.HasUnresolvedRef();
        }

        #endregion

        #region /* FORMATTING */

        /// <summary>
        /// True if the <see cref="Statement"/> has an argument.
        /// </summary>
        public override bool HasArgument
        {
            get { return true; }
        }

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

        #endregion

        #region /* RENDERING */

        protected override void AsTextAfter(CodeWriter writer, RenderFlags flags)
        {
            if (!flags.HasFlag(RenderFlags.NoPostAnnotations))
                AsTextAnnotations(writer, AnnotationFlags.IsPostfix, flags);

            if (_body != null && !flags.HasFlag(RenderFlags.Description))
            {
                // Check for alignment of same-line single-line SwitchItem bodies
                int alignmentOffset = 0;
                foreach (SwitchItem switchItem in _body.Find<SwitchItem>())
                {
                    // If the SwitchItem body is on the same line (and is a single line), then calculate the
                    // common alignment offset.  Ignore any SwitchItems if they're not first-on-line.
                    bool formatOK = false;
                    if (switchItem.IsFirstOnLine)
                    {
                        Block switchItemBody = switchItem.Body;
                        if (switchItemBody != null && switchItemBody.Count > 0 && !switchItemBody.IsFirstOnLine && switchItemBody.IsSingleLine)
                        {
                            formatOK = true;
                            int bodyOffset = switchItem.AsTextLength(RenderFlags.Description | RenderFlags.LengthFlags);
                            if (bodyOffset > alignmentOffset)
                                alignmentOffset = bodyOffset;
                        }
                    }
                    if (!formatOK)
                    {
                        // If the SwitchItem doesn't fit the right pattern, abort the formatting
                        alignmentOffset = 0;
                        break;
                    }
                }

                // If we're aligning, create an alignment state to hold the alignment offset value so the SwitchItems can find it
                if (alignmentOffset > 0)
                    writer.BeginAlignment(this, new[] { alignmentOffset });

                _body.AsText(writer, flags);

                if (alignmentOffset > 0)
                    writer.EndAlignment(this);
            }
        }

        protected override void AsTextArgument(CodeWriter writer, RenderFlags flags)
        {
            _target.AsText(writer, flags);
        }

        #endregion
    }
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

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

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).

| Advertise | Privacy | Mobile
Web04 | 2.8.140721.1 | Last Updated 2 Dec 2012
Article Copyright 2012 by KenBeckett
Everything else Copyright © CodeProject, 1999-2014
Terms of Service
Layout: fixed | fluid