try to make SFUImpl work like JavaFileParser

src/main/java/io/github/astrarre/sfu/SourceFixerUpper.java

@@ -1,6 +1,8 @@
 package io.github.astrarre.sfu;
 
 import io.github.astrarre.sfu.impl.SFUImpl;
+import java.io.IOException;
+import java.nio.charset.Charset;
 import java.nio.file.Path;
 import net.fabricmc.mappingio.tree.MappingTreeView;
 
@@ -10,6 +12,8 @@ static SourceFixerUpper create() {
         return new SFUImpl();
     }
 
+    SourceFixerUpper charset(Charset charset);
+
     SourceFixerUpper mappings(MappingTreeView tree, int srcNamespace, int dstNamespace);
 
     SourceFixerUpper input(Path root);
@@ -20,5 +24,5 @@ static SourceFixerUpper create() {
 
     SourceFixerUpper output(Path output);
 
-    void process();
+    void process() throws IOException;
 }

src/main/java/io/github/astrarre/sfu/impl/JavaFileParser.java

@@ -55,7 +55,8 @@ public void parseJavaSourceFile(Path filePath) throws IOException {
                 codeTree.accept(jsv, null);
                 MemoryMappingTree tree = new MemoryMappingTree();
                 Tiny1Reader.read(Files.newBufferedReader(Path.of("test.tiny")), tree);
-                Remapper remapper = new Remapper(builder, jsv.members, jsv.types, tree, "from", "to");
+                Remapper remapper = new Remapper(builder, jsv.members, jsv.types, tree, tree.getNamespaceId("from"),
+                        tree.getNamespaceId("to"));
                 remapper.apply();
             }
 

src/main/java/io/github/astrarre/sfu/impl/Remapper.java

@@ -10,23 +10,20 @@ public class Remapper {
     public final List<RangeCollectingVisitor.MemberRange> members;
     public final List<RangeCollectingVisitor.TypeRange> types;
     public final MappingTreeView view;
-    public final String from, to;
-    public final int fromIndex, toIndex;
+    public final int srcNamespace, dstNamespace;
 
     public Remapper(StringBuilder builder,
             List<RangeCollectingVisitor.MemberRange> members,
             List<RangeCollectingVisitor.TypeRange> types,
             MappingTreeView view,
-            String from,
-            String to) {
-        this.fromIndex = view.getNamespaceId(from);
-        this.toIndex = view.getNamespaceId(to);
+            int srcNamespace,
+            int dstNamespace) {
+        this.srcNamespace = srcNamespace;
+        this.dstNamespace = dstNamespace;
         this.builder = builder;
         this.members = new ArrayList<>(members);
         this.types = new ArrayList<>(types);
         this.view = view;
-        this.from = from;
-        this.to = to;
         // todo merge into one list before sorting
         // todo resolve from index for proper sorting
         this.members.sort(Comparator.comparingInt(RangeCollectingVisitor.MemberRange::from).reversed());
@@ -36,11 +33,12 @@ public Remapper(StringBuilder builder,
     public void apply() {
         for (RangeCollectingVisitor.MemberRange member : this.members) {
             String name = member.name();
-            var mapping = member.isMethod() ? this.view.getMethod(member.owner(), name, member.desc(), this.fromIndex)
-                    : this.view.getField(member.owner(), name, member.desc(), this.fromIndex);
+            var mapping = member.isMethod()
+                    ? this.view.getMethod(member.owner(), name, member.desc(), this.srcNamespace)
+                    : this.view.getField(member.owner(), name, member.desc(), this.srcNamespace);
 
             if (mapping != null) {
-                String dst = mapping.getDstName(this.toIndex);
+                String dst = mapping.getDstName(this.dstNamespace);
                 int from = member.from(), to = member.to();
                 if (member.to() == -1) {
                     from = this.findStart(from, name, false);

src/main/java/io/github/astrarre/sfu/impl/SFUImpl.java

@@ -1,23 +1,40 @@
 package io.github.astrarre.sfu.impl;
 
 import io.github.astrarre.sfu.SourceFixerUpper;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
+import javax.tools.JavaFileObject;
 import net.fabricmc.mappingio.tree.MappingTreeView;
+import sfu_rpkg.com.sun.source.tree.CompilationUnitTree;
+import sfu_rpkg.com.sun.source.util.JavacTask;
+import sfu_rpkg.com.sun.source.util.Trees;
+import sfu_rpkg.com.sun.tools.javac.api.JavacTool;
+import sfu_rpkg.com.sun.tools.javac.file.JavacFileManager;
+import sfu_rpkg.com.sun.tools.javac.util.Context;
 
 public class SFUImpl implements SourceFixerUpper {
 
+    private Charset charset = Charset.defaultCharset();
     private MappingTreeView tree;
     private int srcNamespace, dstNamespace;
     private Path output;
 
     private final List<Path> inputs, sourcepath, classpath;
 
     public SFUImpl() {
-        inputs = new ArrayList<>();
-        sourcepath = new ArrayList<>();
-        classpath = new ArrayList<>();
+        this.inputs = new ArrayList<>();
+        this.sourcepath = new ArrayList<>();
+        this.classpath = new ArrayList<>();
+    }
+
+    @Override
+    public SourceFixerUpper charset(Charset charset) {
+        this.charset = charset;
+        return this;
     }
 
     @Override
@@ -53,7 +70,32 @@ public SourceFixerUpper output(Path output) {
     }
 
     @Override
-    public void process() {
+    public void process() throws IOException {
+        Context context = new Context();
+        JavacFileManager jcFileManager = new JavacFileManager(context, true, charset);
+        JavacTool javac = JavacTool.create();
+
+        Path filePath = Files.list(inputs.get(0)).filter(Files::isRegularFile).findAny().get();
+
+        Iterable<? extends JavaFileObject> javaFiles = jcFileManager.getJavaFileObjects(filePath);
+        JavacTask jcTask = javac.getTask(null,
+                jcFileManager,
+                null,
+                List.of(),
+                null,
+                javaFiles);
+        Trees trees = Trees.instance(jcTask);
+
+        Iterable<? extends CompilationUnitTree> codeResult = jcTask.parse();
+        jcTask.analyze();
 
+        for (CompilationUnitTree codeTree : codeResult) {
+            var jsv = new RangeCollectingVisitor(trees);
+            codeTree.accept(jsv, null);
+            StringBuilder builder = new StringBuilder(Files.readString(filePath));
+            Remapper remapper = new Remapper(builder, jsv.members, jsv.types, tree, srcNamespace, dstNamespace);
+            remapper.apply();
+            System.out.println(builder);
+        }
     }
 }