Add GetSubTextFromRange to ISourceText

src/Compiler/Facilities/prim-lexing.fs

@@ -6,7 +6,6 @@ namespace FSharp.Compiler.Text
 
 open System
 open System.IO
-open FSharp.Compiler
 
 type ISourceText =
 
@@ -28,6 +27,8 @@ type ISourceText =
 
     abstract CopyTo: sourceIndex: int * destination: char[] * destinationIndex: int * count: int -> unit
 
+    abstract GetSubTextFromRange: range: range -> string
+
 [<Sealed>]
 type StringText(str: string) =
 
@@ -108,6 +109,41 @@ type StringText(str: string) =
         member _.CopyTo(sourceIndex, destination, destinationIndex, count) =
             str.CopyTo(sourceIndex, destination, destinationIndex, count)
 
+        member this.GetSubTextFromRange(range) =
+            let totalAmountOfLines = getLines.Value.Length
+
+            if
+                range.StartLine = 0
+                && range.StartColumn = 0
+                && range.EndLine = 0
+                && range.EndColumn = 0
+            then
+                String.Empty
+            elif
+                range.StartLine < 1
+                || (range.StartLine - 1) > totalAmountOfLines
+                || range.EndLine < 1
+                || (range.EndLine - 1) > totalAmountOfLines
+            then
+                invalidArg (nameof range) "The range is outside the file boundaries"
+            else
+                let sourceText = this :> ISourceText
+                let startLine = range.StartLine - 1
+                let line = sourceText.GetLineString startLine
+
+                if range.StartLine = range.EndLine then
+                    let length = range.EndColumn - range.StartColumn
+                    line.Substring(range.StartColumn, length)
+                else
+                    let firstLineContent = line.Substring(range.StartColumn)
+                    let sb = System.Text.StringBuilder().AppendLine(firstLineContent)
+
+                    for lineNumber in range.StartLine .. range.EndLine - 2 do
+                        sb.AppendLine(sourceText.GetLineString lineNumber) |> ignore
+
+                    let lastLine = sourceText.GetLineString(range.EndLine - 1)
+                    sb.Append(lastLine.Substring(0, range.EndColumn)).ToString()
+
 module SourceText =
 
     let ofString str = StringText(str) :> ISourceText

src/Compiler/Facilities/prim-lexing.fsi

@@ -35,6 +35,10 @@ type ISourceText =
     /// Copies a section of the input to the given destination ad the given index
     abstract CopyTo: sourceIndex: int * destination: char[] * destinationIndex: int * count: int -> unit
 
+    /// Gets a section of the input based on a given range.
+    /// <exception cref="System.ArgumentException">Throws an exception when the input range is outside the file boundaries.</exception>
+    abstract GetSubTextFromRange: range: range -> string
+
 /// Functions related to ISourceText objects
 module SourceText =
 

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.debug.bsl

@@ -10179,6 +10179,7 @@ FSharp.Compiler.Text.ISourceText: Int32 GetLineCount()
 FSharp.Compiler.Text.ISourceText: Int32 Length
 FSharp.Compiler.Text.ISourceText: Int32 get_Length()
 FSharp.Compiler.Text.ISourceText: System.String GetLineString(Int32)
+FSharp.Compiler.Text.ISourceText: System.String GetSubTextFromRange(FSharp.Compiler.Text.Range)
 FSharp.Compiler.Text.ISourceText: System.String GetSubTextString(Int32, Int32)
 FSharp.Compiler.Text.ISourceText: System.Tuple`2[System.Int32,System.Int32] GetLastCharacterPosition()
 FSharp.Compiler.Text.ISourceText: Void CopyTo(Int32, Char[], Int32, Int32)

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.SurfaceArea.netstandard20.release.bsl

@@ -10179,6 +10179,7 @@ FSharp.Compiler.Text.ISourceText: Int32 GetLineCount()
 FSharp.Compiler.Text.ISourceText: Int32 Length
 FSharp.Compiler.Text.ISourceText: Int32 get_Length()
 FSharp.Compiler.Text.ISourceText: System.String GetLineString(Int32)
+FSharp.Compiler.Text.ISourceText: System.String GetSubTextFromRange(FSharp.Compiler.Text.Range)
 FSharp.Compiler.Text.ISourceText: System.String GetSubTextString(Int32, Int32)
 FSharp.Compiler.Text.ISourceText: System.Tuple`2[System.Int32,System.Int32] GetLastCharacterPosition()
 FSharp.Compiler.Text.ISourceText: Void CopyTo(Int32, Char[], Int32, Int32)

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj

@@ -89,6 +89,7 @@
       <Link>RangeTests.fs</Link>
     </Compile>
     <Compile Include="TooltipTests.fs" />
+    <Compile Include="SourceTextTests.fs" />
     <Compile Include="..\service\Program.fs">
       <Link>Program.fs</Link>
     </Compile>

tests/FSharp.Compiler.Service.Tests/SourceTextTests.fs

@@ -0,0 +1,47 @@
+module FSharp.Compiler.Service.Tests.SourceTextTests
+
+open System
+open FSharp.Compiler.Text
+open NUnit.Framework
+
+[<Test>]
+let ``Select text from a single line via the range`` () =
+    let sourceText = SourceText.ofString """
+let a = 2
+"""
+    let m = Range.mkRange "Sample.fs" (Position.mkPos 2 4) (Position.mkPos 2 5)
+    let v = sourceText.GetSubTextFromRange m
+    Assert.AreEqual("a", v)
+
+[<Test>]
+let ``Select text from multiple lines via the range`` () =
+    let sourceText = SourceText.ofString """
+let a b c =
+    // comment
+    2
+"""
+    let m = Range.mkRange "Sample.fs" (Position.mkPos 2 4) (Position.mkPos 4 5)
+    let v = sourceText.GetSubTextFromRange m
+    let sanitized = v.Replace("\r", "")
+    Assert.AreEqual("a b c =\n    // comment\n    2", sanitized)
+
+[<Test>]
+let ``Inconsistent return carriage return correct text`` () =
+    let sourceText =  SourceText.ofString "let a =\r\n    // foo\n    43"
+    let m = Range.mkRange "Sample.fs" (Position.mkPos 1 4) (Position.mkPos 3 6) 
+    let v = sourceText.GetSubTextFromRange m
+    let sanitized = v.Replace("\r", "")
+    Assert.AreEqual("a =\n    // foo\n    43", sanitized)
+
+[<Test>]
+let ``Zero range should return empty string`` () =
+    let sourceText = SourceText.ofString "a"
+    let v = sourceText.GetSubTextFromRange Range.Zero
+    Assert.AreEqual(String.Empty, v)
+
+[<Test>]
+let ``Invalid range should throw argument exception`` () =
+    let sourceText = SourceText.ofString "a"
+    let mInvalid = Range.mkRange "Sample.fs" (Position.mkPos 3 6) (Position.mkPos 1 4)
+    Assert.Throws<ArgumentException>(fun () -> sourceText.GetSubTextFromRange mInvalid |> ignore)
+    |> ignore

tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/SourceText.fs

@@ -64,6 +64,40 @@ module internal SourceText =
 
                 member __.CopyTo(sourceIndex, destination, destinationIndex, count) =
                     sourceText.CopyTo(sourceIndex, destination, destinationIndex, count)
+
+                member this.GetSubTextFromRange range =
+                    let totalAmountOfLines = sourceText.Lines.Count
+
+                    if
+                        range.StartLine = 0
+                        && range.StartColumn = 0
+                        && range.EndLine = 0
+                        && range.EndColumn = 0
+                    then
+                        String.Empty
+                    elif
+                        range.StartLine < 1
+                        || (range.StartLine - 1) > totalAmountOfLines
+                        || range.EndLine < 1
+                        || (range.EndLine - 1) > totalAmountOfLines
+                    then
+                        invalidArg (nameof range) "The range is outside the file boundaries"
+                    else
+                        let startLine = range.StartLine - 1
+                        let line = this.GetLineString startLine
+
+                        if range.StartLine = range.EndLine then
+                            let length = range.EndColumn - range.StartColumn
+                            line.Substring(range.StartColumn, length)
+                        else
+                            let firstLineContent = line.Substring(range.StartColumn)
+                            let sb = System.Text.StringBuilder().AppendLine(firstLineContent)
+
+                            for lineNumber in range.StartLine .. range.EndLine - 2 do
+                                sb.AppendLine(this.GetLineString lineNumber) |> ignore
+
+                            let lastLine = this.GetLineString(range.EndLine - 1)
+                            sb.Append(lastLine.Substring(0, range.EndColumn)).ToString()
             }
 
         sourceText

vsintegration/src/FSharp.Editor/Common/Extensions.fs

@@ -163,6 +163,40 @@ module private SourceText =
 
                   member _.CopyTo(sourceIndex, destination, destinationIndex, count) =
                       sourceText.CopyTo(sourceIndex, destination, destinationIndex, count)
+
+                  member this.GetSubTextFromRange range =
+                      let totalAmountOfLines = sourceText.Lines.Count
+
+                      if
+                          range.StartLine = 0
+                          && range.StartColumn = 0
+                          && range.EndLine = 0
+                          && range.EndColumn = 0
+                      then
+                          String.Empty
+                      elif
+                          range.StartLine < 1
+                          || (range.StartLine - 1) > totalAmountOfLines
+                          || range.EndLine < 1
+                          || (range.EndLine - 1) > totalAmountOfLines
+                      then
+                          invalidArg (nameof range) "The range is outside the file boundaries"
+                      else
+                          let startLine = range.StartLine - 1
+                          let line = this.GetLineString startLine
+
+                          if range.StartLine = range.EndLine then
+                              let length = range.EndColumn - range.StartColumn
+                              line.Substring(range.StartColumn, length)
+                          else
+                              let firstLineContent = line.Substring(range.StartColumn)
+                              let sb = System.Text.StringBuilder().AppendLine(firstLineContent)
+
+                              for lineNumber in range.StartLine .. range.EndLine - 2 do
+                                  sb.AppendLine(this.GetLineString lineNumber) |> ignore
+
+                              let lastLine = this.GetLineString(range.EndLine - 1)
+                              sb.Append(lastLine.Substring(0, range.EndColumn)).ToString()
             }
 
         sourceText