Added LastCharacter method to YString which returns a slice of ju…

…st the last character of a string
martindevans · Feb 24, 2021 · 8863a67 · 8863a67
1 parent 7284605
commit 8863a67
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Showing 9 changed files with 98 additions and 5 deletions.
diff --git a/Yolol.Analysis/Yolol.Analysis.csproj b/Yolol.Analysis/Yolol.Analysis.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.1</TargetFramework>
-    <Version>6.2.3</Version>
+    <Version>6.2.4</Version>
     <LangVersion>8.0</LangVersion>
     <Nullable>enable</Nullable>
     <Platforms>AnyCPU;x64</Platforms>

diff --git a/Yolol/Execution/Rope.cs b/Yolol/Execution/Rope.cs
@@ -112,7 +112,7 @@ private RopeSlice(Rope rope, int start, int length)
             if (length < 0)
                 throw new ArgumentOutOfRangeException(nameof(length), "length < 0");
             if (start + length > rope.Length)
-                throw new ArgumentOutOfRangeException(nameof(length), "start + length >= rope.Length");
+                throw new ArgumentOutOfRangeException(nameof(length), "start + length > rope.Length");
 #endif
         }
 
@@ -201,6 +201,16 @@ public int CompareTo(in Span<char> other)
             return Length - other.Length;
         }
 
+        public RopeSlice PopLast()
+        {
+            if (_rope == null)
+                throw new InvalidOperationException("Attempted to `PopLast` on null `RopeSlice`");
+            if (Length < 1)
+                throw new InvalidOperationException("Attempted to `PopLast` on empty `RopeSlice`");
+
+            return new RopeSlice(_rope, _start + Length - 1, 1);
+        }
+
         public static RopeSlice Concat(in RopeSlice left, in RopeSlice right)
         {
             // If either part of the concat is an empty string (represented by a null rope) return the other half.
@@ -334,7 +344,13 @@ private static RopeSlice Remove(in RopeSlice haystack, int startIndex, int needl
 
             // If left slice _starts_ with the right string we can just offset the start of the slice
             if (startIndex == 0)
-                return new RopeSlice(haystack._rope, haystack._start + needleLength, haystack.Length - needleLength);
+            {
+                var start = haystack._start + needleLength;
+                var length = haystack.Length - needleLength;
+                if (length == 0)
+                    start = 0;
+                return new RopeSlice(haystack._rope, start, length);
+            }
 
             // We'll have to make a new rope and remove it
             var rope = new Rope(haystack.Length);

diff --git a/Yolol/Execution/Value.cs b/Yolol/Execution/Value.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Runtime.InteropServices;
 using Yolol.Execution.Attributes;
 using Yolol.Grammar.AST.Expressions;
 

diff --git a/Yolol/Execution/YString.cs b/Yolol/Execution/YString.cs
@@ -397,5 +397,15 @@ public StaticError Sqrt()
         {
             throw new ExecutionException("Attempted to sqrt a string");
         }
+
+
+        [ErrorMetadata(nameof(WillDecThrow))]
+        public YString LastCharacter()
+        {
+            if (Length == 0)
+                throw new ExecutionException("Attempted to decrement empty string");
+
+            return new YString(_span.PopLast());
+        }
     }
 }
diff --git a/Yolol/Yolol.csproj b/Yolol/Yolol.csproj
@@ -9,7 +9,7 @@
     <PackageProjectUrl>https://github.com/martindevans/Yolol</PackageProjectUrl>
     <RepositoryUrl>https://github.com/martindevans/Yolol</RepositoryUrl>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
-    <Version>11.4.1</Version>
+    <Version>11.5.0</Version>
     <LangVersion>8.0</LangVersion>
     <Nullable>enable</Nullable>
     <Platforms>AnyCPU;x64</Platforms>

diff --git a/YololEmulator.Tests/Expressions/Str/Decrement.cs b/YololEmulator.Tests/Expressions/Str/Decrement.cs
@@ -37,5 +37,27 @@ public void Empty()
                 TestExecutor.Execute("a = \"\"", "b = --a");
             });
         }
+
+        [TestMethod]
+        public void Pop()
+        {
+            var result = TestExecutor.Execute("a = \"abcdefgh\"", "b = a---a");
+
+            var a = result.GetVariable("a");
+            var b = result.GetVariable("b");
+
+            Assert.AreEqual("abcdefg", a.Value.String.ToString());
+            Assert.AreEqual("h", b.Value.String.ToString());
+        }
+
+        [TestMethod]
+        public void DecrementToEmpty()
+        {
+            var result = TestExecutor.Execute("a = \"a\" a--");
+
+            var a = result.GetVariable("a");
+
+            Assert.AreEqual("", a.Value.String.ToString());
+        }
     }
 }
diff --git a/YololEmulator.Tests/Expressions/Str/Subtraction.cs b/YololEmulator.Tests/Expressions/Str/Subtraction.cs
@@ -98,5 +98,17 @@ public void RemoveMidCharacter()
 
             Assert.AreEqual("ac", a.Value.String.ToString());
         }
+
+        [TestMethod]
+        public void SubtractAll()
+        {
+            var result = TestExecutor.Execute("a = \"abcdefgh\"", "b = a-a");
+
+            var a = result.GetVariable("a");
+            var b = result.GetVariable("b");
+
+            Assert.AreEqual("abcdefgh", a.Value.String.ToString());
+            Assert.AreEqual("", b.Value.String.ToString());
+        }
     }
 }
diff --git a/YololEmulator.Tests/Scripts/LadderRepros.cs b/YololEmulator.Tests/Scripts/LadderRepros.cs
@@ -63,5 +63,32 @@ public void ZijkhalStrings()
                 }
             }
         }
+
+        [TestMethod]
+        public void EvilStrings()
+        {
+            var ms = TestExecutor.Execute(
+                "a=\"abcdef\"",
+                "a -= \"a\"",
+                "b = a---a"
+            );
+
+            Assert.AreEqual("bcde", ms.GetVariable("a").Value.ToString());
+            Assert.AreEqual("f", ms.GetVariable("b").Value.ToString());
+        }
+
+        [TestMethod]
+        public void EvilStrings2()
+        {
+            var ms = TestExecutor.Execute(
+                "a=\"abcxabc\"",
+                "b=a b-- b-- b-- b--",
+                "c=a-b"
+            );
+
+            Assert.AreEqual("abcxabc", ms.GetVariable("a").Value.ToString());
+            Assert.AreEqual("abc", ms.GetVariable("b").Value.ToString());
+            Assert.AreEqual("abcx", ms.GetVariable("c").Value.ToString());
+        }
     }
 }
diff --git a/YololEmulator.Tests/YStringTests.cs b/YololEmulator.Tests/YStringTests.cs
@@ -471,5 +471,12 @@ public void EmptyStringEquals()
             var a = new YString("");
             Assert.IsTrue(a.Equals(""));
         }
+
+        [TestMethod]
+        public void PopLastCharacter()
+        {
+            var str = new YString("Hello");
+            Assert.AreEqual("o", str.LastCharacter().ToString());
+        }
     }
 }