Preserve existing custom areas

4 files changed, 126 insertions, 30 deletions

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/CodeWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/CodeWriter.java
index 3e08c85..b8b0709 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/CodeWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/CodeWriter.java
@@ -4,21 +4,92 @@ import java.io.FileWriter;
 import java.io.IOException;
 import java.io.Writer;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
+import java.util.*;
 
 public class CodeWriter implements AutoCloseable {
-    public static CodeWriter file(Path path) throws IOException {
+    public record CustomAreas(
+        Map<String, List<String>> existing,
+        String customAreaStart,
+        String customAreaEnd
+    ) {
+        public static CustomAreas read(
+            String existingString,
+            String customAreaStart,
+            String customAreaEnd
+        ) {
+            var existing = new HashMap<String, List<String>>();
+
+            Iterable<String> lines = () -> existingString.lines().iterator();
+            Optional<String> name = Optional.empty();
+            var customAreaLines = new ArrayList<String>();
+            for (var line : lines) {
+                var trimmedLine = line.trim();
+                if (trimmedLine.startsWith(customAreaStart)) {
+                    name = Optional.of(trimmedLine.substring(customAreaStart.length()));
+                } else if (name.isPresent() && trimmedLine.startsWith(customAreaEnd + name.get())) {
+                    existing.put(name.get(), customAreaLines);
+                    customAreaLines = new ArrayList<>();
+                    name = Optional.empty();
+                } else if (name.isPresent()) {
+                    customAreaLines.add(line);
+                }
+            }
+
+            return new CustomAreas(existing, customAreaStart, customAreaEnd);
+        }
+
+        public static CustomAreas empty(
+            String customAreaStart,
+            String customAreaEnd
+        ) {
+            return new CustomAreas(Map.of(), customAreaStart, customAreaEnd);
+        }
+
+        public Iterable<String> lines(String name) {
+            var lines = this.existing.get(name);
+            if (lines == null) {
+                return List.of();
+            } else {
+                return lines;
+            }
+        }
+    }
+
+    public static CodeWriter file(
+        Path path,
+        String customAreaStart,
+        String customAreaEnd
+    ) throws IOException {
+        var customAreas = readCustomAreas(path, customAreaStart, customAreaEnd);
         Files.createDirectories(path.getParent());
         var writer = new FileWriter(path.toFile());
-        return new CodeWriter(writer);
+        // TODO: warn if custom areas are unused?
+        return new CodeWriter(writer, customAreas);
+    }
+
+    private static CustomAreas readCustomAreas(
+        Path path,
+        String customAreaStart,
+        String customAreaEnd
+    ) throws IOException {
+        try {
+            var contents = Files.readString(path);
+            return CustomAreas.read(contents, customAreaStart, customAreaEnd);
+        } catch (NoSuchFileException exception) {
+            return CustomAreas.empty(customAreaStart, customAreaEnd);
+        }
     }
 
     private final Writer writer;
+    private final CustomAreas customAreas;
     private int indent;
     private boolean pendingIndent;
 
-    public CodeWriter(Writer writer) {
+    public CodeWriter(Writer writer, CustomAreas customAreas) {
         this.writer = writer;
+        this.customAreas = customAreas;
         this.indent = 0;
         this.pendingIndent = false;
     }
@@ -47,6 +118,21 @@ public class CodeWriter implements AutoCloseable {
         this.indent -= 1;
     }
 
+    public void writeCustomArea(String name) throws IOException {
+        this.write(this.customAreas.customAreaStart);
+        this.write(name);
+
+        for (var line : this.customAreas.lines(name)) {
+            this.writer.write("\n");
+            this.write(line);
+        }
+
+        this.newLine();
+        this.write(this.customAreas.customAreaEnd);
+        this.write(name);
+        this.newLine();
+    }
+
     @Override
     public void close() throws Exception {
         this.writer.close();
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
index 77c2ecd..9356519 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/generators/javatypes/JavaTypesGenerator.java
@@ -4,7 +4,6 @@ import org.zwobble.hobgoblin.compiler.ast.DocComment;
 import org.zwobble.hobgoblin.compiler.ast.typed.*;
 import org.zwobble.hobgoblin.compiler.builtins.NativeTypes;
 import org.zwobble.hobgoblin.compiler.config.OutputConfig;
-import org.zwobble.hobgoblin.compiler.output.CodeWriter;
 import org.zwobble.hobgoblin.compiler.output.generators.Generator;
 import org.zwobble.hobgoblin.compiler.output.lang.java.JavaWriter;
 import org.zwobble.hobgoblin.compiler.output.lang.java.ast.*;
@@ -78,7 +77,7 @@ public class JavaTypesGenerator implements Generator {
                 var javaCompilationUnitPath = this.sourceRootDirectory
                     .resolve(String.join(File.separator, javaCompilationUnit.packageName()))
                     .resolve(javaCompilationUnit.typeDeclaration().name() + ".java");
-                try (var writer = new JavaWriter(CodeWriter.file(javaCompilationUnitPath))) {
+                try (var writer = JavaWriter.file(javaCompilationUnitPath)) {
                     writer.writeCompilationUnit(javaCompilationUnit);
                 } catch (Exception e) {
                     // TODO: better handling
@@ -115,7 +114,7 @@ public class JavaTypesGenerator implements Generator {
                             sumDefinition.variants().stream()
                                 .map(variant -> generateTypeRef(variant.type(), context))
                                 .toList(),
-                            JavaCustomArea.EMPTY,
+                            JavaCustomArea.type(generateTypeRef(sumDefinition.type(), context), "body"),
                             sumDefinition.docComment()
                         )
                     );
@@ -168,7 +167,7 @@ public class JavaTypesGenerator implements Generator {
                 ),
                 generateStructDefinitionBuilder(structDefinition, components, context)
             ),
-            JavaCustomArea.EMPTY,
+            JavaCustomArea.type(generateTypeRef(structDefinition.type(), context), "body"),
             structDefinition.docComment()
         );
     }
@@ -216,7 +215,7 @@ public class JavaTypesGenerator implements Generator {
             components,
             List.of(),
             body,
-            JavaCustomArea.EMPTY,
+            JavaCustomArea.type(builderJavaTypeRef, "body"),
             DocComment.EMPTY
         );
     }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
index 9f87e0f..82c2f9b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
@@ -5,8 +5,18 @@ import org.zwobble.hobgoblin.compiler.output.CodeWriter;
 import org.zwobble.hobgoblin.compiler.output.lang.java.ast.*;
 
 import java.io.IOException;
+import java.io.StringWriter;
+import java.nio.file.Path;
 
 public class JavaWriter implements AutoCloseable {
+    public static JavaWriter file(Path path) throws IOException {
+        return new JavaWriter(CodeWriter.file(
+            path,
+            "// Custom area start: ",
+            "// Custom area end: "
+        ));
+    }
+
     private final CodeWriter writer;
 
     public JavaWriter(CodeWriter writer) {
@@ -84,7 +94,7 @@ public class JavaWriter implements AutoCloseable {
         }
 
         this.writer.newLine();
-        this.writeCustomArea("body", classDeclaration.customArea());
+        this.writeCustomArea(classDeclaration.customArea());
 
         this.writer.dedent();
         this.writer.write("}");
@@ -102,19 +112,12 @@ public class JavaWriter implements AutoCloseable {
         }
     }
 
-    private void writeCustomArea(String name, JavaCustomArea javaCustomArea) throws IOException {
-        this.writer.write("// Custom area start: ");
-        this.writer.write(name);
-        this.writer.newLine();
-
-        for (var line : javaCustomArea.lines()) {
-            this.writer.write(line);
-            this.writer.newLine();
-        }
-
-        this.writer.write("// Custom area end: ");
-        this.writer.write(name);
-        this.writer.newLine();
+    private void writeCustomArea(JavaCustomArea customArea) throws IOException {
+        var customAreaName = new StringWriter();
+        writeTypeRef(customArea.type(), customAreaName::write);
+        customAreaName.write(" ");
+        customAreaName.write(customArea.name());
+        this.writer.writeCustomArea(customAreaName.toString());
     }
 
     void writeExpression(JavaExpression expression) throws IOException {
@@ -165,7 +168,7 @@ public class JavaWriter implements AutoCloseable {
         this.writer.write("{");
         this.writer.indent();
         this.writer.newLine();
-        this.writeCustomArea("body", interfaceDeclaration.customArea());
+        this.writeCustomArea(interfaceDeclaration.customArea());
         this.writer.dedent();
         this.writer.write("}");
     }
@@ -271,7 +274,7 @@ public class JavaWriter implements AutoCloseable {
         }
 
         this.writer.newLine();
-        this.writeCustomArea("body", recordDeclaration.customArea());
+        this.writeCustomArea(recordDeclaration.customArea());
 
         this.writer.dedent();
         this.writer.write("}");
@@ -301,6 +304,10 @@ public class JavaWriter implements AutoCloseable {
     }
 
     void writeTypeRef(JavaTypeRef type) throws IOException {
+        writeTypeRef(type, writer::write);
+    }
+
+    private static void writeTypeRef(JavaTypeRef type, WriteString writer) throws IOException {
         for (var part : type.packageName()) {
             writer.write(part);
             writer.write(".");
@@ -316,14 +323,14 @@ public class JavaWriter implements AutoCloseable {
             writer.write("<");
             writeWithSeparator(
                 type.args(),
-                this::writeTypeRef,
+                arg -> writeTypeRef(arg, writer),
                 () -> writer.write(", ")
             );
             writer.write(">");
         }
     }
 
-    private <T> void writeWithSeparator(
+    private static <T> void writeWithSeparator(
         Iterable<T> iterable,
         WriteElement<T> writeElement,
         WriteSeparator writeSeparator
@@ -349,4 +356,8 @@ public class JavaWriter implements AutoCloseable {
     interface WriteSeparator {
         void write() throws IOException;
     }
+
+    interface WriteString {
+        void write(String string) throws IOException;
+    }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaCustomArea.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaCustomArea.java
index 42d38d1..51e3096 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaCustomArea.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaCustomArea.java
@@ -1,7 +1,7 @@
 package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
 
-import java.util.List;
-
-public record JavaCustomArea(List<String> lines) {
-    public static final JavaCustomArea EMPTY = new JavaCustomArea(List.of());
+public record JavaCustomArea(JavaTypeRef type, String name) {
+    public static JavaCustomArea type(JavaTypeRef type, String name) {
+        return new JavaCustomArea(type, name);
+    }
 }