Philiprehberger.TextDiff

Line-by-line text diff using Myers' algorithm with unified diff output and structured DiffResult objects.

Installation

dotnet add package Philiprehberger.TextDiff

Usage

using Philiprehberger.TextDiff;

var result = Diff.Compare("hello\nworld", "hello\nearth");
Console.WriteLine($"Changes: {result.HasChanges}, Added: {result.AddedCount}, Removed: {result.RemovedCount}");

Unified Diff Output

using Philiprehberger.TextDiff;

var oldText = "alpha\nbeta\ngamma\ndelta";
var newText = "alpha\nbeta\nepsilon\ndelta";

var unified = Diff.Unified(oldText, newText, "file-v1.txt", "file-v2.txt", context: 2);
Console.WriteLine(unified);
// --- file-v1.txt
// +++ file-v2.txt
// @@ -1,4 +1,4 @@
//  alpha
//  beta
// -gamma
// +epsilon
//  delta

Diff Statistics

using Philiprehberger.TextDiff;

var result = Diff.Compare("a\nb\nc", "a\nx\nc");

Console.WriteLine($"Additions: {result.Statistics.Additions}");
Console.WriteLine($"Deletions: {result.Statistics.Deletions}");
Console.WriteLine($"Modifications: {result.Statistics.Modifications}");
Console.WriteLine($"Change %: {result.Statistics.ChangePercentage}");

Diff Options

using Philiprehberger.TextDiff;

var options = new DiffOptions
{
    IgnoreWhitespace = true,
    IgnoreCase = true,
    IgnoreBlankLines = true
};

var result = Diff.Compare("  Hello  \n\nWorld", "hello\nworld", options);
Console.WriteLine($"Has changes: {result.HasChanges}"); // False

Character-Level Inline Diff

using Philiprehberger.TextDiff;

var changes = InlineDiff.ComputeCharacterDiff("hello world", "hello earth");

foreach (var change in changes)
{
    var marker = change.Type switch
    {
        ChangeType.Equal => " ",
        ChangeType.Delete => "-",
        ChangeType.Insert => "+"
    };
    Console.Write($"[{marker}{change.Text}]");
}
// [ hello ][- ][+e][-w][-o][-r][-l][-d][+a][+r][+t][+h]

Word-Level Diff

using Philiprehberger.TextDiff;

var changes = InlineDiff.ComputeWordDiff("the quick brown fox", "the slow brown cat");

foreach (var change in changes)
{
    if (change.Type == ChangeType.Delete)
        Console.Write($"[-{change.Text}]");
    else if (change.Type == ChangeType.Insert)
        Console.Write($"[+{change.Text}]");
    else
        Console.Write(change.Text);
}
// the [-quick][+slow] brown [-fox][+cat]

API

Diff

Method	Description
Compare(oldText, newText, options?)	Compares two texts and returns a DiffResult with lines, counts, and statistics
Unified(oldText, newText, oldLabel?, newLabel?, context?, options?)	Produces a unified diff string with ---, +++, and @@ headers
Lines(oldText, newText, options?)	Returns a list of DiffLine entries with change types and line numbers

DiffResult

Property	Type	Description
Lines	IReadOnlyList<DiffLine>	The individual diff lines
AddedCount	int	Number of added lines
RemovedCount	int	Number of removed lines
UnchangedCount	int	Number of unchanged lines
HasChanges	bool	Whether the texts differ
Statistics	DiffStatistics	Detailed diff statistics

DiffLine

Property	Type	Description
Type	DiffLineType	Added, Removed, or Unchanged
Content	string	The text content of the line
OldLineNumber	int?	1-based line number in the old text
NewLineNumber	int?	1-based line number in the new text

DiffStatistics

Property	Type	Description
Additions	int	Number of added lines
Deletions	int	Number of deleted lines
Modifications	int	Number of modified lines (paired remove/add sequences)
ChangePercentage	double	Percentage of lines that changed (0.0 to 100.0)

DiffOptions

Property	Type	Default	Description
IgnoreWhitespace	bool	false	Ignore leading and trailing whitespace
IgnoreCase	bool	false	Ignore case differences
IgnoreBlankLines	bool	false	Skip blank lines when comparing
Mode	DiffMode	Line	Diff granularity: Line, Word, or Character

InlineDiff

Method	Description
ComputeCharacterDiff(oldText, newText)	Character-level diff returning InlineChange segments
ComputeWordDiff(oldText, newText)	Word-level diff returning InlineChange segments

InlineChange

Property	Type	Description
Type	ChangeType	Equal, Insert, or Delete
Text	string	The text content of the segment

DiffMode

Value	Description
Line	Compare text line by line
Word	Compare text word by word
Character	Compare text character by character

Development

dotnet build src/Philiprehberger.TextDiff.csproj --configuration Release

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License

MIT