3 files changed, 27 insertions, 10 deletions

diff --git a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaReader.java b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaReader.java
index a53793d3..ddbee76f 100644
--- a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaReader.java
+++ b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaReader.java
@@ -5,8 +5,14 @@ import com.google.common.collect.Queues;
 import cuchaz.enigma.throwables.MappingConflict;
 import cuchaz.enigma.throwables.MappingParseException;
 
-import java.io.*;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.util.Deque;
+import java.util.function.Supplier;
 
 public class MappingsEnigmaReader {
 
@@ -39,7 +45,11 @@ public class MappingsEnigmaReader {
         }
 
         public Mappings readFile(Mappings mappings, File file) throws IOException, MappingParseException {
-                try (BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(file), Charsets.UTF_8))) {
+                return readFileStream(mappings, new FileInputStream(file), file::getAbsolutePath);
+        }
+
+        public Mappings readFileStream(Mappings mappings, InputStream stream, Supplier<String> filenameSupplier) throws IOException, MappingParseException {
+                try (BufferedReader in = new BufferedReader(new InputStreamReader(stream, Charsets.UTF_8))) {
                         Deque<Object> mappingStack = Queues.newArrayDeque();
 
                         int lineNumber = 0;
@@ -87,7 +97,7 @@ public class MappingsEnigmaReader {
 
                                                         // inner class
                                                         if (!(mappingStack.peek() instanceof ClassMapping)) {
-                                                                throw new MappingParseException(file, lineNumber, "Unexpected CLASS entry here!");
+                                                                throw new MappingParseException(filenameSupplier, lineNumber, "Unexpected CLASS entry here!");
                                                         }
 
                                                         classMapping = readClass(parts, true);
@@ -96,26 +106,26 @@ public class MappingsEnigmaReader {
                                                 mappingStack.push(classMapping);
                                         } else if (token.equalsIgnoreCase("FIELD")) {
                                                 if (mappingStack.isEmpty() || !(mappingStack.peek() instanceof ClassMapping)) {
-                                                        throw new MappingParseException(file, lineNumber, "Unexpected FIELD entry here!");
+                                                        throw new MappingParseException(filenameSupplier, lineNumber, "Unexpected FIELD entry here!");
                                                 }
                                                 ((ClassMapping) mappingStack.peek()).addFieldMapping(readField(parts));
                                         } else if (token.equalsIgnoreCase("METHOD")) {
                                                 if (mappingStack.isEmpty() || !(mappingStack.peek() instanceof ClassMapping)) {
-                                                        throw new MappingParseException(file, lineNumber, "Unexpected METHOD entry here!");
+                                                        throw new MappingParseException(filenameSupplier, lineNumber, "Unexpected METHOD entry here!");
                                                 }
                                                 MethodMapping methodMapping = readMethod(parts);
                                                 ((ClassMapping) mappingStack.peek()).addMethodMapping(methodMapping);
                                                 mappingStack.push(methodMapping);
                                         } else if (token.equalsIgnoreCase("ARG")) {
                                                 if (mappingStack.isEmpty() || !(mappingStack.peek() instanceof MethodMapping)) {
-                                                        throw new MappingParseException(file, lineNumber, "Unexpected ARG entry here!");
+                                                        throw new MappingParseException(filenameSupplier, lineNumber, "Unexpected ARG entry here!");
                                                 }
                                                 ((MethodMapping) mappingStack.peek()).addArgumentMapping(readArgument(parts));
                                         }
                                 } catch (ArrayIndexOutOfBoundsException | IllegalArgumentException ex) {
-                                        throw new MappingParseException(file, lineNumber, "Malformed line:\n" + line);
+                                        throw new MappingParseException(filenameSupplier, lineNumber, "Malformed line:\n" + line);
                                 } catch (MappingConflict e) {
-                                        throw new MappingParseException(file, lineNumber, e.getMessage());
+                                        throw new MappingParseException(filenameSupplier, lineNumber, e.getMessage());
                                 }
                         }
                         return mappings;
diff --git a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
index 1e1c4ddc..b29990f5 100644
--- a/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
+++ b/src/main/java/cuchaz/enigma/mapping/MappingsEnigmaWriter.java
@@ -85,7 +85,7 @@ public class MappingsEnigmaWriter {
                 }
         }
 
-        private void write(PrintWriter out, ClassMapping classMapping, int depth) throws IOException {
+        protected void write(PrintWriter out, ClassMapping classMapping, int depth) throws IOException {
                 if (classMapping.getDeobfName() == null) {
                         out.format("%sCLASS %s%s\n", getIndent(depth), classMapping.getObfFullName(),
                                         classMapping.getModifier() == Mappings.EntryModifier.UNCHANGED ? "" : classMapping.getModifier().getFormattedName());
@@ -134,7 +134,7 @@ public class MappingsEnigmaWriter {
                 out.format("%sARG %d %s\n", getIndent(depth), localVariableMapping.getIndex(), localVariableMapping.getName());
         }
 
-        private <T extends Comparable<T>> List<T> sorted(Iterable<T> classes) {
+        protected <T extends Comparable<T>> List<T> sorted(Iterable<T> classes) {
                 List<T> out = new ArrayList<>();
                 for (T t : classes) {
                         out.add(t);
diff --git a/src/main/java/cuchaz/enigma/throwables/MappingParseException.java b/src/main/java/cuchaz/enigma/throwables/MappingParseException.java
index cc5f650a..b7e6d426 100644
--- a/src/main/java/cuchaz/enigma/throwables/MappingParseException.java
+++ b/src/main/java/cuchaz/enigma/throwables/MappingParseException.java
@@ -12,6 +12,7 @@
 package cuchaz.enigma.throwables;
 
 import java.io.File;
+import java.util.function.Supplier;
 
 public class MappingParseException extends Exception {
 
@@ -25,6 +26,12 @@ public class MappingParseException extends Exception {
                 filePath = file.getAbsolutePath();
         }
 
+        public MappingParseException(Supplier<String> filenameProvider, int line, String message) {
+                this.line = line;
+                this.message = message;
+                filePath = filenameProvider.get();
+        }
+
         @Override
         public String getMessage() {
                 return "Line " + line + ": " + message + " in file " + filePath;