better slicing semantics for strings

git-svn-id: https://svn.codehaus.org/boo/trunk@965 2c1201b4-01cd-e047-a400-b836ae1fbc61
bamboo · Sep 10, 2004 · 2dcea69 · 2dcea69
1 parent cb8ccb9
commit 2dcea69
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Showing 5 changed files with 69 additions and 12 deletions.
diff --git a/il b/il
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+mono build/booc.exe -out:build/il.exe "$@" && monodis build/il.exe
diff --git a/il.bat b/il.bat
@@ -1,3 +1,3 @@
 @echo off
-build\booc.exe /out:build\il.exe %1 %2 %3 %4 %5 %6 %7 %8 %9
+build\booc.exe -out:build\il.exe %1 %2 %3 %4 %5 %6 %7 %8 %9
 ildasm /text build\il.exe
diff --git a/src/Boo.Lang.Compiler/Steps/ProcessMethodBodies.cs b/src/Boo.Lang.Compiler/Steps/ProcessMethodBodies.cs
@@ -59,6 +59,8 @@ public class ProcessMethodBodies : AbstractNamespaceSensitiveVisitorCompilerStep
 
 		IMethod RuntimeServices_Mid;
 
+		IMethod RuntimeServices_NormalizeStringIndex;
+
 		IMethod RuntimeServices_GetRange1;
 
 		IMethod RuntimeServices_GetRange2;
@@ -152,7 +154,8 @@ virtual protected void InitializeMemberCache()
 			RuntimeServices_GetRange1 = ResolveMethod(TypeSystemServices.RuntimeServicesType, "GetRange1");
 			RuntimeServices_GetRange2 = ResolveMethod(TypeSystemServices.RuntimeServicesType, "GetRange2"); 			
 			RuntimeServices_Len = ResolveMethod(TypeSystemServices.RuntimeServicesType, "Len");
-			RuntimeServices_Mid = ResolveMethod(TypeSystemServices.RuntimeServicesType, "Mid");			
+			RuntimeServices_Mid = ResolveMethod(TypeSystemServices.RuntimeServicesType, "Mid");
+			RuntimeServices_NormalizeStringIndex = ResolveMethod(TypeSystemServices.RuntimeServicesType, "NormalizeStringIndex");			
 			RuntimeServices_GetEnumerable = ResolveMethod(TypeSystemServices.RuntimeServicesType, "GetEnumerable");			
 			RuntimeServices_op_Equality = (IMethod)TypeSystemServices.Map(Types.RuntimeServices.GetMethod("op_Equality", new Type[] { Types.Object, Types.Object }));
 			Array_get_Length = ResolveProperty(TypeSystemServices.ArrayType, "Length").GetGetMethod();
@@ -1279,6 +1282,15 @@ void BindComplexArraySlicing(SlicingExpression node)
 			}
 		}
 
+		bool NeedsNormalization(Expression index)
+		{
+			if (NodeType.IntegerLiteralExpression == index.NodeType)
+			{
+				return ((IntegerLiteralExpression)index).Value < 0;
+			}
+			return true;
+		}
+
 		void BindComplexStringSlicing(SlicingExpression node)
 		{
 			if (CheckComplexSlicingParameters(node))
@@ -1287,8 +1299,30 @@ void BindComplexStringSlicing(SlicingExpression node)
 
 				if (null == node.End || node.End == OmittedExpression.Default)
 				{
-					mie = CodeBuilder.CreateMethodInvocation(node.Target, String_Substring_Int);
-					mie.Arguments.Add(node.Begin);
+					if (NeedsNormalization(node.Begin))
+					{
+						mie = CodeBuilder.CreateEvalInvocation(node.LexicalInfo);
+						mie.ExpressionType = TypeSystemServices.StringType;
+
+						LocalVariable temp = DeclareTempLocal(TypeSystemServices.StringType);
+						mie.Arguments.Add(
+							CodeBuilder.CreateAssignment(
+								CodeBuilder.CreateReference(temp),
+								node.Target));
+
+						mie.Arguments.Add(
+							CodeBuilder.CreateMethodInvocation(
+								CodeBuilder.CreateReference(temp),
+								String_Substring_Int,
+								CodeBuilder.CreateMethodInvocation(
+									RuntimeServices_NormalizeStringIndex,
+									CodeBuilder.CreateReference(temp),
+									node.Begin)));
+					}
+					else
+					{
+						mie = CodeBuilder.CreateMethodInvocation(node.Target, String_Substring_Int, node.Begin);
+					}
 				}
 				else
 				{	
@@ -3867,6 +3901,18 @@ ReferenceExpression CreateTempLocal(LexicalInfo li, IType type)
 			return reference;
 		}
 
+		LocalVariable DeclareTempLocal(IType localType)
+		{
+			Local local  = new Local();
+			local.Name = "___temp" + _context.AllocIndex();
+			local.PrivateScope = true;
+
+			LocalVariable entity = new LocalVariable(local, localType);
+			local.Entity = entity;
+			_currentMethod.Method.Locals.Add(local);
+			return entity;
+		}
+
 		LocalVariable DeclareLocal(Node sourceNode, Local local, IType localType)
 		{			
 			LocalVariable tag = new LocalVariable(local, localType);

diff --git a/src/Boo/Lang/RuntimeServices.cs b/src/Boo/Lang/RuntimeServices.cs
@@ -134,14 +134,8 @@ public static int Len(object obj)
 
 		public static string Mid(string s, int begin, int end)
 		{
-			if (begin < 0)
-			{
-				begin += s.Length;
-			}
-			if (end < 0)
-			{
-				end += s.Length;
-			}
+			begin = NormalizeStringIndex(s, begin);
+			end = NormalizeStringIndex(s, end);
 			return s.Substring(begin, end-begin);
 		}
 
@@ -184,6 +178,11 @@ public static int NormalizeArrayIndex(Array array, int index)
 			return index < 0 ? array.Length + index : index;
 		}
 
+		public static int NormalizeStringIndex(string s, int index)
+		{
+			return index < 0 ? s.Length + index : index;
+		}
+
 		public static IEnumerable GetEnumerable(object enumerable)
 		{
 			if (null == enumerable)

diff --git a/tests/testcases/integration/slicing-11.boo b/tests/testcases/integration/slicing-11.boo
@@ -0,0 +1,9 @@
+import NUnit.Framework
+
+a = "Gooooooooood niiiiiiiiigh ding ding ding ding ding ding"
+Assert.AreEqual("Go", a[:2])
+Assert.AreEqual("Go", a[0:2])
+Assert.AreEqual("ding", a[-4:])
+Assert.AreEqual("din", a[-4:-1])
+
+