Parser and reader performance improvements

Improves performance a little over roughly 2x.
exodrifter · Apr 14, 2018 · 1f899bd · 1f899bd
1 parent 965cbad
commit 1f899bd
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Showing 3 changed files with 77 additions and 67 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Changed
+* Compiler performance improvements
+
 ### Fixed
 * Fix `elif` and `else` compilation errors
 

diff --git a/Language/Parser.cs b/Language/Parser.cs
@@ -109,7 +109,7 @@ public List<Node> Compile(Reader reader, int? targetDepth = null)
 				string command;
 				if (temp.Peek() == '$')
 				{
-					command = "" + temp.Read();
+					command = temp.Read().ToString();
 				}
 				else
 				{
@@ -171,7 +171,7 @@ public List<Node> Compile(Reader reader, int? targetDepth = null)
 				}
 
 				// Catch up reader
-				reader.Read(temp.Index - reader.Index);
+				reader.Update(temp);
 				temp = GetTempOnNextLine(reader);
 			}
 
@@ -357,7 +357,7 @@ private Condition CompileIf(Reader reader, int depth)
 				temp.Skip();
 
 				// Catch up reader
-				reader.Read(temp.Index - reader.Index);
+				reader.Update(temp);
 
 				var elif = CompileElif(reader, depth);
 				return new Condition(new If(exp, children, elif));
@@ -368,7 +368,7 @@ private Condition CompileIf(Reader reader, int depth)
 				temp.Skip();
 
 				// Catch up reader
-				reader.Read(temp.Index - reader.Index);
+				reader.Update(temp);
 
 				var @else = CompileElse(reader, depth);
 				return new Condition(new If(exp, children, @else));
@@ -393,7 +393,7 @@ private Elif CompileElif(Reader reader, int depth)
 				temp.Skip();
 
 				// Catch up reader
-				reader.Read(temp.Index - reader.Index);
+				reader.Update(temp);
 
 				var elif = CompileElif(reader, depth);
 				return new Elif(exp, children, elif);
@@ -404,7 +404,7 @@ private Elif CompileElif(Reader reader, int depth)
 				temp.Skip();
 
 				// Catch up reader
-				reader.Read(temp.Index - reader.Index);
+				reader.Update(temp);
 
 				var @else = CompileElse(reader, depth);
 				return new Elif(exp, children, @else);
@@ -806,13 +806,13 @@ public List<Token> TokenizeExpression(Reader reader)
 				// Catch up the reader
 				if (temp != null)
 				{
-					reader.Read(temp.Index - reader.Index);
+					reader.Update(temp);
 				}
 				temp = new Reader(reader);
 
 				// Skip whitespace
 				temp.Skip();
-				if (!temp.EOF && temp.Peek() == '\n')
+				while (!temp.EOF && temp.Peek() == '\n')
 				{
 					temp.NextLine();
 					temp.Skip();

diff --git a/Language/Reader.cs b/Language/Reader.cs
@@ -150,29 +150,32 @@ public bool HasMatch(string match, bool caseSensitive = false)
 				return false;
 			}
 
-			// Read from current position
-			string str = "";
+			// Check if the match length is possible
+			if (index + match.Length > script.Length)
+			{
+				return false;
+			}
+
+			// Check each character one by one
 			for (int i = 0; i < match.Length; ++i)
 			{
-				if (index + i < script.Length)
+				var a = match[i];
+				var b = script[index + i];
+
+				// Case sensitivity
+				if (!caseSensitive)
 				{
-					str += script[index + i];
+					a = char.ToLowerInvariant(a);
+					b = char.ToLowerInvariant(b);
 				}
-			}
 
-			// Case sensitivity
-			if (!caseSensitive)
-			{
-				match = match.ToLower();
-				str = str.ToLower();
+				if (a != b)
+				{
+					return false;
+				}
 			}
 
-			// Check match
-			if (match == str)
-			{
-				return true;
-			}
-			return false;
+			return true;
 		}
 
 		/// <summary>
@@ -218,25 +221,7 @@ public char Read()
 				throw new ReadException(this);
 			}
 
-			char ret = script[index];
-
-			// Update state
-			if (ret == '\t')
-			{
-				col += GetTabDelta();
-			}
-			else if (ret != '\n')
-			{
-				col++;
-			}
-			else
-			{
-				line++;
-				col = 1;
-			}
-
-			index++;
-			return ret;
+			return ReadInternal();
 		}
 
 		/// <summary>
@@ -247,14 +232,19 @@ public char Read()
 		/// <returns>The next string in the script.</returns>
 		public string Read(int length)
 		{
-			var builder = new StringBuilder();
+			if (index + length > script.Length)
+			{
+				throw new ReadException(this);
+			}
+
+			var ret = script.Substring(index, length);
 
 			for (int i = 0; i < length; ++i)
 			{
-				builder.Append(Read());
+				ReadInternal();
 			}
 
-			return builder.ToString();
+			return ret;
 		}
 
 		/// <summary>
@@ -268,41 +258,46 @@ public string Read(int length)
 		/// <returns>The string found.</returns>
 		public string ReadUntil(params char[] arr)
 		{
-			var builder = new StringBuilder();
+			var start = index;
+			var length = 0;
 
 			while (!EOF)
 			{
 				// Check if reading should stop
-				var ch = script[index];
-				if (arr.Contains(ch))
+				if (arr.Contains(script[index]))
 				{
 					break;
 				}
 
-				// Read
-				builder.Append(ch);
+				ReadInternal();
+				length++;
+			}
 
-				// Update state
-				switch (ch)
-				{
-					case '\n':
-						line++;
-						col = 1;
-						break;
+			return script.Substring(start, length);
+		}
 
-					case '\t':
-						col += GetTabDelta();
-						break;
+		private char ReadInternal()
+		{
+			var ch = script[index++];
 
-					default:
-						col++;
-						break;
-				}
+			// Update state
+			switch (ch)
+			{
+				case '\n':
+					line++;
+					col = 1;
+					break;
 
-				index++;
+				case '\t':
+					col += GetTabDelta();
+					break;
+
+				default:
+					col++;
+					break;
 			}
 
-			return builder.ToString();
+			return ch;
 		}
 
 		/// <summary>
@@ -347,6 +342,18 @@ public int Skip()
 
 		#region Util
 
+		/// <summary>
+		/// Overwrites this reader's state with another. Does not check if the
+		/// readers are reading from the same source with the same
+		/// configuration.
+		/// </summary>
+		internal void Update(Reader other)
+		{
+			this.line = other.line;
+			this.col = other.col;
+			this.index = other.index;
+		}
+
 		/// <summary>
 		/// Returns the number of spaces the column position should move in
 		/// order to insert a tab.