Tyrrrz#13 - CommandLineSplitter utility, used to split input from pow…

…ershell

CliFx.Tests/CommandLineUtilsSpecs.cs

@@ -0,0 +1,22 @@
+using CliFx.Utils;
+using FluentAssertions;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace CliFx.Tests
+{
+    public class CommandLineSplitterSpecs 
+    {
+        [Theory]
+        [InlineData("MyApp alpha beta", new string[] { "MyApp", "alpha", "beta" })]
+        [InlineData("MyApp \"alpha with spaces\" \"beta with spaces\"", new string[] { "MyApp", "alpha with spaces", "beta with spaces" })]
+        [InlineData("MyApp 'alpha with spaces' beta", new string[] { "MyApp", "'alpha", "with", "spaces'", "beta" })]
+        [InlineData("MyApp \\\\\\alpha \\\\\\\\\"beta", new string[] { "MyApp", "\\\\\\alpha", "\\\\beta" })]
+        [InlineData("MyApp \\\\\\\\\\\"alpha \\\"beta", new string[] { "MyApp", "\\\\\"alpha", "\"beta" })]
+        public void Suggestion_service_can_emulate_GetCommandLineArgs(string input, string[] expected)
+        {
+            var output = CommandLineSplitter.Split(input);
+            output.Should().BeEquivalentTo(expected);
+        }
+    }
+}

CliFx/CliFx.csproj

@@ -44,4 +44,10 @@
     </ItemGroup>
   </Target>
 
+  <ItemGroup>
+    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
+      <_Parameter1>CliFx.Tests</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
+
 </Project>

CliFx/Utils/CommandLineSplitter.cs

@@ -0,0 +1,108 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace CliFx.Utils
+{
+    internal static class CommandLineSplitter
+    {
+        /// <summary>
+        ///  Reproduces Environment.GetCommandLineArgs() as per https://docs.microsoft.com/en-us/dotnet/api/system.environment.getcommandlineargs?view=net-5.0
+        ///
+        ///  Input at the command line Resulting command line arguments
+        ///  MyApp alpha beta                                MyApp, alpha, beta
+        ///  MyApp "alpha with spaces" "beta with spaces"    MyApp, alpha with spaces, beta with spaces
+        ///  MyApp 'alpha with spaces' beta                  MyApp, 'alpha, with, spaces', beta
+        ///  MyApp \\\alpha \\\\"beta	                     MyApp, \\\alpha, \\beta
+        ///  MyApp \\\\\"alpha \"beta	                     MyApp, \\"alpha, "beta
+        ///
+        ///  Used to parse autocomplete text as it is passed in as a single argument by Powershell
+        ///        
+        /// </summary>
+        public static string[] Split(string s)
+        {
+            int escapeSequenceLength = 0;
+            int escapeSequenceEnd = 0;
+            bool ignoreSpaces = false;
+
+            var tokens = new List<string>();
+            StringBuilder tokenBuilder = new StringBuilder();
+
+            for (int i = 0; i < s.Length; i++)
+            {
+                // determine how long the escape character sequence is 
+                if (s[i] == '\\' && i > escapeSequenceEnd)
+                {
+                    for (int j = i; j < s.Length; j++)
+                    {
+                        if (s[j] == '\\')
+                        {
+                            continue;
+                        }
+                        else if (s[j] != '\"')
+                        {
+                            // edge case: \\\alpha --> \\\alpha (no escape)
+                            escapeSequenceLength = 0;
+                            break;
+                        }
+
+                        escapeSequenceLength = j - i;
+
+                        // edge case: \\\\"beta -> \\beta
+                        // treat the " as an escape character so that we skip over it
+                        if (escapeSequenceLength == 4)
+                        {
+                            escapeSequenceLength = 6;
+                        }
+                        else
+                        {
+                            // capture the escaped character in our escape sequence
+                            escapeSequenceLength++;
+                        }
+
+                        escapeSequenceEnd = i + escapeSequenceLength;
+                        break;
+                    }
+                }
+
+                if (escapeSequenceLength > 0 && escapeSequenceLength % 2 == 0)
+                {
+                    // skip escape characters
+                }
+                else
+                {
+                    bool characterIsEscaped = escapeSequenceLength != 0;
+
+                    // edge case: '"' character is used to divide tokens eg: MyApp "alpha with spaces" "beta with spaces" 
+                    // skip the '"' character
+                    if (!characterIsEscaped && s[i] == '"')
+                    {
+                        ignoreSpaces = !ignoreSpaces;
+                    }
+                    // edge case: ' ' character is used to divide tokens
+                    else if (!characterIsEscaped && char.IsWhiteSpace(s[i]) && !ignoreSpaces)
+                    {
+                        tokens.Add(tokenBuilder.ToString());
+                        tokenBuilder.Clear();
+                    }
+                    else
+                    {
+                        tokenBuilder.Append(s[i]);
+                    }
+                }
+
+                if (escapeSequenceLength > 0)
+                {
+                    escapeSequenceLength--;
+                }
+            }
+
+            var token = tokenBuilder.ToString();
+            if (!string.IsNullOrWhiteSpace(token))
+            {
+                tokens.Add(token);
+            }
+            return tokens.ToArray();
+        }
+    }
+}