//
-// assign.cs: Assignment representation for the IL tree.
+// assign.cs: Assignments.
//
// Author:
// Miguel de Icaza (miguel@ximian.com)
+// Martin Baulig (martin@gnome.org)
//
-// (C) 2001 Ximian, Inc.
+// (C) 2001, 2002 Ximian, Inc.
//
using System;
using System.Reflection;
using System.Reflection.Emit;
-namespace CIR {
- public class Assign : ExpressionStatement {
- Expression target, source;
- Location l;
+namespace Mono.CSharp {
+
+ /// <summary>
+ /// This interface is implemented by expressions that can be assigned to.
+ /// </summary>
+ /// <remarks>
+ /// This interface is implemented by Expressions whose values can not
+ /// store the result on the top of the stack.
+ ///
+ /// Expressions implementing this (Properties, Indexers and Arrays) would
+ /// perform an assignment of the Expression "source" into its final
+ /// location.
+ ///
+ /// No values on the top of the stack are expected to be left by
+ /// invoking this method.
+ /// </remarks>
+ public interface IAssignMethod {
+ //
+ // This method will emit the code for the actual assignment
+ //
+ void EmitAssign (EmitContext ec, Expression source);
+
+ //
+ // This method is invoked before any code generation takes
+ // place, and it is a mechanism to inform that the expression
+ // will be invoked more than once, and that the method should
+ // use temporary values to avoid having side effects
+ //
+ // Example: a [ g () ] ++
+ //
+ void CacheTemporaries (EmitContext ec);
+ }
+
+ /// <summary>
+ /// An Expression to hold a temporary value.
+ /// </summary>
+ /// <remarks>
+ /// The LocalTemporary class is used to hold temporary values of a given
+ /// type to "simulate" the expression semantics on property and indexer
+ /// access whose return values are void.
+ ///
+ /// The local temporary is used to alter the normal flow of code generation
+ /// basically it creates a local variable, and its emit instruction generates
+ /// code to access this value, return its address or save its value.
+ /// </remarks>
+ public class LocalTemporary : Expression, IMemoryLocation {
+ LocalBuilder builder;
+ public LocalTemporary (EmitContext ec, Type t)
+ {
+ type = t;
+ eclass = ExprClass.Value;
+ loc = Location.Null;
+ builder = ec.GetTemporaryStorage (t);
+ }
+
+ public void Release (EmitContext ec)
+ {
+ ec.FreeTemporaryStorage (builder);
+ builder = null;
+ }
+
+ public LocalTemporary (LocalBuilder b, Type t)
+ {
+ type = t;
+ eclass = ExprClass.Value;
+ loc = Location.Null;
+ builder = b;
+ }
+
+ public override Expression DoResolve (EmitContext ec)
+ {
+ return this;
+ }
+
+ public override void Emit (EmitContext ec)
+ {
+ ec.ig.Emit (OpCodes.Ldloc, builder);
+ }
+
+ public void Store (EmitContext ec)
+ {
+ ec.ig.Emit (OpCodes.Stloc, builder);
+ }
+
+ public void AddressOf (EmitContext ec, AddressOp mode)
+ {
+ ec.ig.Emit (OpCodes.Ldloca, builder);
+ }
+ }
+
+ /// <summary>
+ /// The Assign node takes care of assigning the value of source into
+ /// the expression represented by target.
+ /// </summary>
+ public class Assign : ExpressionStatement {
+ protected Expression target, source, real_source;
+ protected LocalTemporary temp = null, real_temp = null;
+ protected Assign embedded = null;
+ protected bool is_embedded = false;
+ protected bool must_free_temp = false;
+
public Assign (Expression target, Expression source, Location l)
{
this.target = target;
- this.source = source;
- this.l = l;
+ this.source = this.real_source = source;
+ this.loc = l;
+ }
+
+ protected Assign (Assign embedded, Location l)
+ : this (embedded.target, embedded.source, l)
+ {
+ this.is_embedded = true;
}
public Expression Target {
}
}
+ public static void error70 (EventInfo ei, Location l)
+ {
+ Report.Error (70, l, "The event '" + ei.Name +
+ "' can only appear on the left-side of a += or -= (except when" +
+ " used from within the type '" + ei.DeclaringType + "')");
+ }
+
+ //
+ // Will return either `this' or an instance of `New'.
+ //
public override Expression DoResolve (EmitContext ec)
{
- target = target.Resolve (ec);
- source = source.Resolve (ec);
+ // Create an embedded assignment if our source is an assignment.
+ if (source is Assign)
+ source = embedded = new Assign ((Assign) source, loc);
- if (target == null || source == null)
+ real_source = source = source.Resolve (ec);
+ if (source == null)
+ return null;
+
+ //
+ // This is used in an embedded assignment.
+ // As an example, consider the statement "A = X = Y = Z".
+ //
+ if (is_embedded && !(source is Constant)) {
+ // If this is the innermost assignment (the "Y = Z" in our example),
+ // create a new temporary local, otherwise inherit that variable
+ // from our child (the "X = (Y = Z)" inherits the local from the
+ // "Y = Z" assignment).
+ if (embedded == null)
+ real_temp = temp = new LocalTemporary (ec, source.Type);
+ else
+ temp = embedded.temp;
+
+ // Set the source to the new temporary variable.
+ // This means that the following target.ResolveLValue () will tell
+ // the target to read it's source value from that variable.
+ source = temp;
+ }
+
+ // If we have an embedded assignment, use the embedded assignment's temporary
+ // local variable as source.
+ if (embedded != null)
+ source = (embedded.temp != null) ? embedded.temp : embedded.source;
+
+ target = target.ResolveLValue (ec, source);
+
+ if (target == null)
return null;
Type target_type = target.Type;
- Type source_type = source.Type;
+ Type source_type = real_source.Type;
- type = target_type;
+ // If we're an embedded assignment, our parent will reuse our source as its
+ // source, it won't read from our target.
+ if (is_embedded)
+ type = source_type;
+ else
+ type = target_type;
eclass = ExprClass.Value;
-
+
//
// If we are doing a property assignment, then
// set the `value' field on the property, and Resolve
//
if (target is PropertyExpr){
PropertyExpr property_assign = (PropertyExpr) target;
-
+
+ if (source_type != target_type){
+ source = ConvertImplicitRequired (ec, source, target_type, loc);
+ if (source == null)
+ return null;
+ }
+
+ //
+ // FIXME: Maybe handle this in the LValueResolve
+ //
if (!property_assign.VerifyAssignable ())
return null;
-
+
return this;
}
+
+ if (target is IndexerAccess) {
+ return this;
+ }
+
+ if (target is EventExpr) {
+ EventInfo ei = ((EventExpr) target).EventInfo;
+
+ Expression ml = MemberLookup (
+ ec, ec.ContainerType, ei.Name,
+ MemberTypes.Event, AllBindingFlags | BindingFlags.DeclaredOnly, loc);
+
+ if (ml == null) {
+ //
+ // If this is the case, then the Event does not belong
+ // to this Type and so, according to the spec
+ // is allowed to only appear on the left hand of
+ // the += and -= operators
+ //
+ // Note that target will not appear as an EventExpr
+ // in the case it is being referenced within the same type container;
+ // it will appear as a FieldExpr in that case.
+ //
+
+ if (!(source is Binary)) {
+ error70 (ei, loc);
+ return null;
+ } else {
+ Binary tmp = ((Binary) source);
+ if (tmp.Oper != Binary.Operator.Addition &&
+ tmp.Oper != Binary.Operator.Subtraction) {
+ error70 (ei, loc);
+ return null;
+ }
+ }
+ }
+ }
- if (source is New && target_type.IsSubclassOf (TypeManager.value_type)){
+ if (source is New && target_type.IsValueType){
New n = (New) source;
n.ValueTypeVariable = target;
-
return n;
}
+
+ if (target.eclass != ExprClass.Variable && target.eclass != ExprClass.EventAccess){
+ Report.Error (131, loc,
+ "Left hand of an assignment must be a variable, " +
+ "a property or an indexer");
+ return null;
+ }
+
+ if ((source.eclass == ExprClass.Type) && (source is TypeExpr)) {
+ source.Error118 ("variable or value");
+ return null;
+ } else if (source is MethodGroupExpr){
+ ((MethodGroupExpr) source).ReportUsageError ();
+ return null;
+ }
+
+ if (target_type == source_type)
+ return this;
- if (target_type != source_type){
- source = ConvertImplicitRequired (ec, source, target_type, l);
- if (source == null)
+ //
+ // If this assignemnt/operator was part of a compound binary
+ // operator, then we allow an explicit conversion, as detailed
+ // in the spec.
+ //
+
+ if (this is CompoundAssign){
+ CompoundAssign a = (CompoundAssign) this;
+
+ Binary b = source as Binary;
+ if (b != null && b.IsBuiltinOperator){
+ //
+ // 1. if the source is explicitly convertible to the
+ // target_type
+ //
+
+ source = ConvertExplicit (ec, source, target_type, loc);
+ if (source == null){
+ Error_CannotConvertImplicit (loc, source_type, target_type);
+ return null;
+ }
+
+ //
+ // 2. and the original right side is implicitly convertible to
+ // the type of target_type.
+ //
+ if (StandardConversionExists (a.original_source, target_type))
+ return this;
+
+ Error_CannotConvertImplicit (loc, a.original_source.Type, target_type);
return null;
+ }
}
- if (!(target is LValue)){
- Report.Error (131, l, "Left hand of an assignment must be a variable, a property or an indexer");
+ source = ConvertImplicitRequired (ec, source, target_type, loc);
+ if (source == null)
return null;
- }
+ // If we're an embedded assignment, we need to create a new temporary variable
+ // for the converted value. Our parent will use this new variable as its source.
+ // The same applies when we have an embedded assignment - in this case, we need
+ // to convert our embedded assignment's temporary local variable to the correct
+ // type and store it in a new temporary local.
+ if (is_embedded || embedded != null) {
+ type = target_type;
+ temp = new LocalTemporary (ec, type);
+ must_free_temp = true;
+ }
+
return this;
}
- void Emit (EmitContext ec, bool is_statement)
+ Expression EmitEmbedded (EmitContext ec)
{
- ILGenerator ig = ec.ig;
- ExprClass eclass = target.ExprClass;
+ // Emit an embedded assignment.
- if (eclass == ExprClass.Variable){
+ if (real_temp != null) {
+ // If we're the innermost assignment, `real_source' is the right-hand
+ // expression which gets assigned to all the variables left of it.
+ // Emit this expression and store its result in real_temp.
+ real_source.Emit (ec);
+ real_temp.Store (ec);
+ }
- //
- // If it is an instance field, load the this pointer
- //
- if (target is FieldExpr){
- FieldExpr fe = (FieldExpr) target;
-
- if (!fe.FieldInfo.IsStatic)
- ig.Emit (OpCodes.Ldarg_0);
- }
+ if (embedded != null)
+ embedded.EmitEmbedded (ec);
+ // This happens when we've done a type conversion, in this case source will be
+ // the expression which does the type conversion from real_temp.
+ // So emit it and store the result in temp; this is the var which will be read
+ // by our parent.
+ if (temp != real_temp) {
source.Emit (ec);
+ temp.Store (ec);
+ }
- if (!is_statement)
- ig.Emit (OpCodes.Dup);
+ Expression temp_source = (temp != null) ? temp : source;
+ ((IAssignMethod) target).EmitAssign (ec, temp_source);
+ return temp_source;
+ }
- ((LValue) target).Store (ec);
- } else if (eclass == ExprClass.PropertyAccess){
- PropertyExpr pe = (PropertyExpr) target;
+ void ReleaseEmbedded (EmitContext ec)
+ {
+ if (embedded != null)
+ embedded.ReleaseEmbedded (ec);
- if (is_statement){
- pe.Value = source;
- pe.Emit (ec);
- } else {
- LocalTemporary tempo;
-
- tempo = new LocalTemporary (ec, source.Type);
+ if (real_temp != null)
+ real_temp.Release (ec);
- pe.Value = tempo;
- source.Emit (ec);
- tempo.Store (ec);
- target.Emit (ec);
+ if (must_free_temp)
+ temp.Release (ec);
+ }
- tempo.Emit (ec);
+ void Emit (EmitContext ec, bool is_statement)
+ {
+ if (target is EventExpr) {
+ ((EventExpr) target).EmitAddOrRemove (ec, source);
+ return;
+ }
+
+ //
+ // FIXME! We need a way to "probe" if the process can
+ // just use `dup' to propagate the result
+ //
+ IAssignMethod am = (IAssignMethod) target;
+
+ if (this is CompoundAssign){
+ am.CacheTemporaries (ec);
+ }
+
+ Expression temp_source;
+ if (embedded != null) {
+ temp_source = embedded.EmitEmbedded (ec);
+
+ if (temp != null) {
+ source.Emit (ec);
+ temp.Store (ec);
+ temp_source = temp;
}
- } else if (eclass == ExprClass.IndexerAccess){
-
- throw new Exception ("Can not assign to indexers yet");
+ } else
+ temp_source = source;
+
+ if (is_statement)
+ am.EmitAssign (ec, temp_source);
+ else {
+ LocalTemporary tempo;
+
+ tempo = new LocalTemporary (ec, source.Type);
+
+ temp_source.Emit (ec);
+ tempo.Store (ec);
+ am.EmitAssign (ec, tempo);
+ tempo.Emit (ec);
+ tempo.Release (ec);
+ }
+
+ if (embedded != null) {
+ if (temp != null)
+ temp.Release (ec);
+ embedded.ReleaseEmbedded (ec);
}
}
Emit (ec, true);
}
}
+
+
+ //
+ // This class is used for compound assignments.
+ //
+ class CompoundAssign : Assign {
+ Binary.Operator op;
+ public Expression original_source;
+
+ public CompoundAssign (Binary.Operator op, Expression target, Expression source, Location l)
+ : base (target, source, l)
+ {
+ original_source = source;
+ this.op = op;
+ }
+
+ public Expression ResolveSource (EmitContext ec)
+ {
+ return original_source.Resolve (ec);
+ }
+
+ public override Expression DoResolve (EmitContext ec)
+ {
+ target = target.ResolveLValue (ec, source);
+ if (target == null)
+ return null;
+
+ original_source = original_source.Resolve (ec);
+ if (original_source == null)
+ return null;
+
+ //
+ // Only now we can decouple the original source/target
+ // into a tree, to guarantee that we do not have side
+ // effects.
+ //
+ source = new Binary (op, target, original_source, loc);
+ return base.DoResolve (ec);
+ }
+ }
}
projects / mono.git / blobdiff