Skip to content

Commit

Permalink
Replace boxing ArrayList in PathParser, improve performance, decrease…
Browse files Browse the repository at this point in the history 
… allocs (#9631)

* replace boxing ArrayList with List<SourceValueInfo>

* seal PathParser, save 8 bytes on a singleton instance

* simplify adding Indexer/Property parser

* use ToArray() over CopyTo() (halgab)
  • Loading branch information
@h3xds1nz
h3xds1nz authored Jan 23, 2025
1 parent d6ae821 commit acfc83e
Showing 1 changed file with 39 additions and 57 deletions.
96 changes: 39 additions & 57 deletions src/Microsoft.DotNet.Wpf/src/PresentationFramework/MS/Internal/Data/PathParser.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,11 @@
// Description: Parser for the Path of a (CLR) binding
//

using System.Collections;
using System;
using System.Text; // StringBuilder
using System.Windows;
using System.Collections.Generic;

using MS.Utility; // FrugalList

namespace MS.Internal.Data
Expand Down Expand Up @@ -56,13 +58,14 @@ public IndexerParamInfo(string paren, string value)
}
}

internal class PathParser
internal sealed class PathParser
{
string _error;
public String Error { get { return _error; } }
void SetError(string id, params object[] args) { _error = SR.Format(SR.GetResourceString(id), args); }
private string _error;
public string Error => _error;
private void SetError(string id, params object[] args) => _error = SR.Format(SR.GetResourceString(id), args);

enum State { Init, DrillIn, Prop, Done };
private enum State { Init, DrillIn, Prop, Done };
private enum IndexerState { BeginParam, ParenString, ValueString, Done }

// Each level of the path consists of
// a property or indexer:
Expand All @@ -80,7 +83,7 @@ enum State { Init, DrillIn, Prop, Done };

public SourceValueInfo[] Parse(string path)
{
_path = (path != null) ? path.Trim() : String.Empty;
_path = (path != null) ? path.Trim() : string.Empty;
_n = _path.Length;

if (_n == 0)
Expand All @@ -93,14 +96,14 @@ public SourceValueInfo[] Parse(string path)
_index = 0;
_drillIn = DrillIn.IfNeeded;

_al.Clear();
_sourceValueInfos.Clear();
_error = null;
_state = State.Init;

while (_state != State.Done)
{
char c = (_index < _n) ? _path[_index] : NullChar;
if (Char.IsWhiteSpace(c))
if (char.IsWhiteSpace(c))
{
++_index;
continue;
Expand Down Expand Up @@ -138,48 +141,31 @@ public SourceValueInfo[] Parse(string path)
break;
default:
SetError(nameof(SR.PathSyntax), _path.Substring(0, _index), _path.Substring(_index));
return EmptyInfo;
return Array.Empty<SourceValueInfo>();
}
_state = State.Prop;
break;

case State.Prop:
bool isIndexer = false;
switch (c)
{
case '[':
isIndexer = true;
case '[': // Indexer follows
AddIndexer();
break;
default:
default: // Property follows
AddProperty();
break;
}

if (isIndexer)
AddIndexer();
else
AddProperty();
}

break;
}
}


SourceValueInfo[] result;

if (_error == null)
{
result = new SourceValueInfo[_al.Count];
_al.CopyTo(result);
}
else
{
result = EmptyInfo;
}

return result;
// If an error has occurred, we return an empty array instead
return _error is null ? _sourceValueInfos.ToArray() : Array.Empty<SourceValueInfo>();
}

void AddProperty()
private void AddProperty()
{
int start = _index;
int level = 0;
Expand Down Expand Up @@ -216,15 +202,12 @@ void AddProperty()
? new SourceValueInfo(SourceValueType.Property, _drillIn, name)
: new SourceValueInfo(SourceValueType.Direct, _drillIn, (string)null);

_al.Add(info);
_sourceValueInfos.Add(info);

StartNewLevel();
}


enum IndexerState { BeginParam, ParenString, ValueString, Done }

void AddIndexer()
private void AddIndexer()
{
// indexer args are parsed by a (sub-) state machine with four
// states. The string is a comma-separated list of params, each
Expand Down Expand Up @@ -253,7 +236,7 @@ void AddIndexer()
return;
}

Char c = _path[_index++];
char c = _path[_index++];

// handle the escape character - set the flag for the next character
if (c == EscapeChar && !escaped)
Expand All @@ -276,7 +259,7 @@ void AddIndexer()
// '(' introduces optional paren string
state = IndexerState.ParenString;
}
else if (Char.IsWhiteSpace(c))
else if (char.IsWhiteSpace(c))
{
// ignore leading white space
}
Expand Down Expand Up @@ -324,7 +307,7 @@ void AddIndexer()
--level;
}
}
else if (Char.IsWhiteSpace(c))
else if (char.IsWhiteSpace(c))
{
// add white space, but trim it later if it's trailing
valueStringBuilder.Append(c);
Expand Down Expand Up @@ -371,15 +354,13 @@ void AddIndexer()
}

// assemble the final result
SourceValueInfo info = new SourceValueInfo(
SourceValueType.Indexer,
_drillIn, paramList);
_al.Add(info);
SourceValueInfo info = new(SourceValueType.Indexer, _drillIn, paramList);
_sourceValueInfos.Add(info);

StartNewLevel();
}

void StartNewLevel()
private void StartNewLevel()
{
_state = (_index < _n) ? State.DrillIn : State.Done;
_drillIn = DrillIn.Never;
Expand All @@ -390,15 +371,16 @@ private static bool IsSpecialChar(char ch)
return ch == '.' || ch == '/' || ch == '[' || ch == ']';
}

State _state;
string _path;
int _index;
int _n;
DrillIn _drillIn;
ArrayList _al = new ArrayList();
const char NullChar = Char.MinValue;
const char EscapeChar = '^';
static SourceValueInfo[] EmptyInfo = Array.Empty<SourceValueInfo>();
private State _state;
private string _path;
private int _index;
private int _n;
private DrillIn _drillIn;

private const char NullChar = char.MinValue;
private const char EscapeChar = '^';

private readonly List<SourceValueInfo> _sourceValueInfos = new();
}
}

0 comments on commit acfc83e

Please sign in to comment.