feat: text-based diffing method

Author: pmbittner

src/main/java/org/variantsync/diffdetective/variation/diff/VariationDiff.java

@@ -105,9 +105,20 @@ public static VariationDiff<DiffLinesLabel> fromFile(final Path p, VariationDiff
      * @throws DiffParseException if {@code diff} couldn't be parsed
      */
     public static VariationDiff<DiffLinesLabel> fromDiff(final String diff, final VariationDiffParseOptions parseOptions) throws DiffParseException {
-        final VariationDiff<DiffLinesLabel> tree = VariationDiffParser.createVariationDiff(diff, parseOptions);
-        tree.setSource(new PatchString(diff));
-        return tree;
+        final VariationDiff<DiffLinesLabel> d;
+        try {
+            d = VariationDiffParser.createVariationDiff(diff, parseOptions);
+        } catch (DiffParseException e) {
+            Logger.error("""
+                            Could not parse diff:
+                            
+                            {}
+                            """,
+                    diff);
+            throw e;
+        }
+        d.setSource(new PatchString(diff));
+        return d;
     }
 
     /**

src/main/java/org/variantsync/diffdetective/variation/diff/construction/JGitDiff.java

@@ -1,21 +1,21 @@
 package org.variantsync.diffdetective.variation.diff.construction;
 
+import org.apache.commons.io.IOUtils;
 import org.eclipse.jgit.diff.*;
-import org.tinylog.Logger;
 import org.variantsync.diffdetective.diff.git.GitDiffer;
 import org.variantsync.diffdetective.diff.result.DiffParseException;
 import org.variantsync.diffdetective.variation.DiffLinesLabel;
 import org.variantsync.diffdetective.variation.diff.Time;
 import org.variantsync.diffdetective.variation.diff.VariationDiff;
 import org.variantsync.diffdetective.variation.diff.parse.VariationDiffParseOptions;
-import org.variantsync.diffdetective.variation.diff.parse.VariationDiffParser;
-import org.variantsync.diffdetective.variation.diff.source.PatchString;
 
 import java.io.BufferedReader;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.regex.Pattern;
 
 /**
@@ -26,25 +26,42 @@ public final class JGitDiff {
     private final static Pattern NO_NEWLINE_AT_END_OF_FILE = Pattern.compile("\n\\\\ No newline at end of file");
 
     private JGitDiff() {}
+
+    /**
+     * Creates a text-based diff from two line-based text inputs.
+     * Uses JGit to diff the two files using the specified {@code options}.
+     * @param beforeFile Path to text file before the change.
+     * @param afterFile Path to text file after the change.
+     * @param algorithm Specification of which algorithm to use for diffing with JGit.
+     * @return A variation diff comprising the changes.
+     * @throws IOException when JGit fails in differencing
+     */
+    public static String textDiff(
+            Path beforeFile,
+            Path afterFile,
+            DiffAlgorithm.SupportedAlgorithm algorithm
+    ) throws IOException {
+        try (BufferedReader b = Files.newBufferedReader(beforeFile);
+             BufferedReader a = Files.newBufferedReader(afterFile)
+        ) {
+            return textDiff(IOUtils.toString(b), IOUtils.toString(a), algorithm);
+        }
+    }
 
     /**
-     * Creates a variation diff from to line-based text inputs.
-     * Expects variability to be implemented via C preprocessor in those lines.
-     * Uses JGit to diff the two files using the specified {@code options}, and afterwards, creates the variation diff.
+     * Creates a text-based diff from two line-based text inputs.
+     * Uses JGit to diff the two files using the specified {@code options}.
      * @param linesBefore State of annotated lines before the change.
      * @param linesAfter State of annotated lines after the change.
      * @param algorithm Specification of which algorithm to use for diffing with JGit.
-     * @param options various options for parsing
      * @return A variation diff comprising the changes.
      * @throws IOException when JGit fails in differencing
-     * @throws DiffParseException when DiffDetective fails in parsing the JGit diff to a variation diff
      */
-    public static VariationDiff<DiffLinesLabel> diff(
+    public static String textDiff(
             String linesBefore,
             String linesAfter,
-            DiffAlgorithm.SupportedAlgorithm algorithm,
-            VariationDiffParseOptions options
-    ) throws IOException, DiffParseException {
+            DiffAlgorithm.SupportedAlgorithm algorithm
+    ) throws IOException {
         final RawText[] text = new RawText[]{
                 new RawText(linesBefore.getBytes()),
                 new RawText(linesAfter.getBytes())
@@ -93,23 +110,33 @@ Using our own formatter without diff headers (paired with a maximum context (?))
                 new BufferedReader(new StringReader(textDiff))
         );
 
-        
         textDiff = NO_NEWLINE_AT_END_OF_FILE.matcher(textDiff).replaceAll("");
         //textDiff = HUNK_HEADER_REGEX.matcher(textDiff).replaceAll("");
-
-        final VariationDiff<DiffLinesLabel> d;
-        try {
-            d = VariationDiffParser.createVariationDiff(textDiff, options);
-        } catch (DiffParseException e) {
-            Logger.error("""
-                            Could not parse diff:
-                            
-                            {}
-                            """,
-                    textDiff);
-            throw e;
-        }
-        d.setSource(new PatchString(textDiff));
-        return d;
+        
+        return textDiff;
+    }
+    
+    /**
+     * Creates a variation diff from to line-based text inputs.
+     * Expects variability to be implemented via C preprocessor in those lines.
+     * Uses JGit to diff the two files using the specified {@code options}, and afterwards, creates the variation diff.
+     * Creates a variation diff from to line-based text inputs.
+     * First creates a line-based diff with {@link #textDiff(String, String, DiffAlgorithm.SupportedAlgorithm)}
+     * and then parses that diff with {@link VariationDiff#fromDiff(String, VariationDiffParseOptions)}.
+     * @param linesBefore State of annotated lines before the change.
+     * @param linesAfter State of annotated lines after the change.
+     * @param algorithm Specification of which algorithm to use for diffing with JGit.
+     * @param options various options for parsing
+     * @return A variation diff comprising the changes.
+     * @throws IOException when JGit fails in differencing
+     * @throws DiffParseException when DiffDetective fails in parsing the JGit diff to a variation diff
+     */
+    public static VariationDiff<DiffLinesLabel> diff(
+            String linesBefore,
+            String linesAfter,
+            DiffAlgorithm.SupportedAlgorithm algorithm,
+            VariationDiffParseOptions options
+    ) throws IOException, DiffParseException {
+        return VariationDiff.fromDiff(textDiff(linesBefore, linesAfter, algorithm), options);
     }
 }