Include original line in parse exception

3 files changed, 24 insertions, 5 deletions

diff --git a/src/main/java/org/zwobble/mammoth/internal/styles/parsing/ParseException.java b/src/main/java/org/zwobble/mammoth/internal/styles/parsing/ParseException.java
index 832a673..40fb16b 100644
--- a/src/main/java/org/zwobble/mammoth/internal/styles/parsing/ParseException.java
+++ b/src/main/java/org/zwobble/mammoth/internal/styles/parsing/ParseException.java
@@ -1,7 +1,22 @@
 package org.zwobble.mammoth.internal.styles.parsing;
 
 public class ParseException extends RuntimeException {
-    public ParseException(int lineNumber, Token token, String message) {
-        super("error reading style map at line " + lineNumber + ", character " + (token.getCharacterIndex() + 1) + ": " + message);
+    public ParseException(String line, int lineNumber, Token token, String message) {
+        super(generateMessage(line, lineNumber, token, message));
+    }
+
+    private static String generateMessage(String line, int lineNumber, Token token, String message) {
+        return "error reading style map at line " + lineNumber + ", character " + (token.getCharacterIndex() + 1) +
+            ": " + message + "\n\n" +
+            line + "\n" +
+            repeatString(" ", token.getCharacterIndex()) + "^";
+    }
+
+    private static String repeatString(String value, int times) {
+        StringBuilder builder = new StringBuilder();
+        for (int i = 0; i < times; i++) {
+            builder.append(value);
+        }
+        return builder.toString();
     }
 }
diff --git a/src/main/java/org/zwobble/mammoth/internal/styles/parsing/StyleMapParser.java b/src/main/java/org/zwobble/mammoth/internal/styles/parsing/StyleMapParser.java
index c22e1e6..d1ceb72 100644
--- a/src/main/java/org/zwobble/mammoth/internal/styles/parsing/StyleMapParser.java
+++ b/src/main/java/org/zwobble/mammoth/internal/styles/parsing/StyleMapParser.java
@@ -18,10 +18,11 @@ public class StyleMapParser {
     public static StyleMap parseStyleMappings(List<String> lines) {
         StyleMapBuilder styleMap = StyleMap.builder();
         for (int lineIndex = 0; lineIndex < lines.size(); lineIndex += 1) {
+            String line = lines.get(lineIndex);
             try {
-                handleLine(styleMap, lines.get(lineIndex));
+                handleLine(styleMap, line);
             } catch (LineParseException exception) {
-                throw new ParseException(lineIndex + 1, exception.getToken(), exception.getMessage());
+                throw new ParseException(line, lineIndex + 1, exception.getToken(), exception.getMessage());
             }
         }
         return styleMap.build();
diff --git a/src/test/java/org/zwobble/mammoth/tests/MammothTests.java b/src/test/java/org/zwobble/mammoth/tests/MammothTests.java
index f0210bf..455fa0c 100644
--- a/src/test/java/org/zwobble/mammoth/tests/MammothTests.java
+++ b/src/test/java/org/zwobble/mammoth/tests/MammothTests.java
@@ -198,7 +198,10 @@ public class MammothTests {
             () -> new DocumentConverter().addStyleMap("p =>\np[style-name=] =>"));
         assertThat(
             exception.getMessage(),
-            equalTo("error reading style map at line 2, character 14: expected token of type STRING but was of type CLOSE_SQUARE_BRACKET"));
+            equalTo(
+                "error reading style map at line 2, character 14: expected token of type STRING but was of type CLOSE_SQUARE_BRACKET\n\n" +
+                "p[style-name=] =>\n" +
+                "             ^"));
     }
 
     @Test