Pass delimiter information to ValueSource

This closes #76

Author: kwin

src/main/java/org/codehaus/plexus/interpolation/AbstractDelegatingValueSource.java

@@ -34,14 +34,22 @@ protected ValueSource getDelegate() {
         return delegate;
     }
 
+    @Override
+    public Object getValue(String expression, String delimiterStart, String delimiterEnd) {
+        return getDelegate().getValue(expression, delimiterStart, delimiterEnd);
+    }
+
+    @Override
     public Object getValue(String expression) {
         return getDelegate().getValue(expression);
     }
 
+    @Override
     public void clearFeedback() {
         delegate.clearFeedback();
     }
 
+    @Override
     public List getFeedback() {
         return delegate.getFeedback();
     }

src/main/java/org/codehaus/plexus/interpolation/RegexBasedInterpolator.java

@@ -177,23 +177,36 @@ public String interpolate(String input, String thisPrefixPattern, RecursionInter
 
         int realExprGroup = 2;
         Pattern expressionPattern;
+        final String expressionDelimiterStart;
+        final String expressionDelimiterEnd;
         if (startRegex != null || endRegex != null) {
             if (thisPrefixPattern == null) {
                 expressionPattern = getPattern(startRegex + endRegex);
                 realExprGroup = 1;
             } else {
                 expressionPattern = getPattern(startRegex + thisPrefixPattern + endRegex);
             }
+            expressionDelimiterStart = startRegex;
+            expressionDelimiterEnd = endRegex;
 
-        } else if (thisPrefixPattern != null) {
-            expressionPattern = getPattern("\\$\\{(" + thisPrefixPattern + ")?(.+?)\\}");
         } else {
-            expressionPattern = getPattern(DEFAULT_REGEXP);
-            realExprGroup = 1;
+            expressionDelimiterStart = "${";
+            expressionDelimiterEnd = "}";
+            if (thisPrefixPattern != null) {
+                expressionPattern = getPattern("\\$\\{(" + thisPrefixPattern + ")?(.+?)\\}");
+            } else {
+                expressionPattern = getPattern(DEFAULT_REGEXP);
+                realExprGroup = 1;
+            }
         }
-
         try {
-            return interpolate(input, recursionInterceptor, expressionPattern, realExprGroup);
+            return interpolate(
+                    input,
+                    recursionInterceptor,
+                    expressionPattern,
+                    expressionDelimiterStart,
+                    expressionDelimiterEnd,
+                    realExprGroup);
         } finally {
             if (!cacheAnswers) {
                 clearAnswers();
@@ -228,7 +241,12 @@ private Pattern getPattern(String regExp) {
      * @todo Ensure unresolvable expressions don't trigger infinite recursion.
      */
     private String interpolate(
-            String input, RecursionInterceptor recursionInterceptor, Pattern expressionPattern, int realExprGroup)
+            String input,
+            RecursionInterceptor recursionInterceptor,
+            Pattern expressionPattern,
+            String expressionDelimiterStart,
+            String expressionDelimiterEnd,
+            int realExprGroup)
             throws InterpolationException {
         if (input == null) {
             // return empty String to prevent NPE too
@@ -256,11 +274,17 @@ private String interpolate(
                 for (ValueSource vs : valueSources) {
                     if (value != null) break;
 
-                    value = vs.getValue(realExpr);
+                    value = vs.getValue(realExpr, expressionDelimiterStart, expressionDelimiterEnd);
                 }
 
                 if (value != null) {
-                    value = interpolate(String.valueOf(value), recursionInterceptor, expressionPattern, realExprGroup);
+                    value = interpolate(
+                            String.valueOf(value),
+                            recursionInterceptor,
+                            expressionPattern,
+                            expressionDelimiterStart,
+                            expressionDelimiterEnd,
+                            realExprGroup);
 
                     if (postProcessors != null && !postProcessors.isEmpty()) {
                         for (InterpolationPostProcessor postProcessor : postProcessors) {

src/main/java/org/codehaus/plexus/interpolation/StringSearchInterpolator.java

@@ -163,7 +163,7 @@ private String interpolate(String input, RecursionInterceptor recursionIntercept
                             if (value != null) {
                                 break;
                             }
-                            value = valueSource.getValue(realExpr);
+                            value = valueSource.getValue(realExpr, startExpr, endExpr);
 
                             if (value != null && value.toString().contains(wholeExpr)) {
                                 bestAnswer = value;

src/main/java/org/codehaus/plexus/interpolation/ValueSource.java

@@ -25,8 +25,21 @@
 public interface ValueSource {
 
     /**
+     * Returns a value resolved from an expression. The return value is recursively resolved via {@link Interpolator#interpolate(String)}, i.e. might contain expressions as well.
      * @param expression The string expression.
-     * @return the value related to the expression, or null if not found.
+     * @param expressionStartDelimiter A valid start delimiter of the expression to be used with the calling {@link Interpolator} (by default <code>${</code>).
+     * @param expressionEndDelimiter   A valid end delimiter of the expression to be used with the calling {@link Interpolator} (by default <code>}</code>).
+     * @return the value related to the expression, or {@code null} if not found. This value might contain other expressions separated by {@code expressionStartDelimiter} and {@code expressionEndDelimiter}
+     * @since 1.28
+     */
+    default Object getValue(String expression, String expressionStartDelimiter, String expressionEndDelimiter) {
+        return getValue(expression);
+    }
+
+    /**
+     * @param expression The string expression.
+     * @return the value related to the expression, or {@code null} if not found.
+     * @see #getValue(String, String, String)
      */
     public Object getValue(String expression);
 

src/main/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolator.java

@@ -201,7 +201,7 @@ private String interpolate(String input, RecursionInterceptor recursionIntercept
                     for (ValueSource vs : valueSources) {
                         if (value != null) break;
 
-                        value = vs.getValue(realExpr);
+                        value = vs.getValue(realExpr, startExpr, endExpr);
 
                         if (value != null && value.toString().contains(wholeExpr)) {
                             bestAnswer = value;

src/test/java/org/codehaus/plexus/interpolation/RegexBasedInterpolatorTest.java

@@ -80,6 +80,28 @@ public void testShouldResolveByContextValue() throws InterpolationException {
         assertEquals("this is a testVar", result);
     }
 
+    @Test
+    public void testDelimitersPassedToValueSource() throws InterpolationException {
+        RegexBasedInterpolator interpolator = new RegexBasedInterpolator();
+        interpolator.addValueSource(new AbstractValueSource(false) {
+
+            @Override
+            public Object getValue(String expression, String expressionStartDelimiter, String expressionEndDelimiter) {
+                assertEquals("${", expressionStartDelimiter);
+                assertEquals("}", expressionEndDelimiter);
+                return expression;
+            }
+
+            @Override
+            public Object getValue(String expression) {
+                fail("This method is not supposed to be called");
+                return null;
+            }
+        });
+
+        assertEquals("test", interpolator.interpolate("${test}"));
+    }
+
     @Test
     public void testShouldResolveByEnvar() throws IOException, InterpolationException {
         OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {

src/test/java/org/codehaus/plexus/interpolation/StringSearchInterpolatorTest.java

@@ -94,6 +94,30 @@ public void testLongDelimitersWithNoContext() throws InterpolationException {
         assertEquals(result, interpolator.interpolate(src));
     }
 
+    @Test
+    public void testLongDelimitersPassedToValueSource() throws InterpolationException {
+        String src = "<expression>test</expression>";
+
+        StringSearchInterpolator interpolator = new StringSearchInterpolator("<expression>", "</expression>");
+        interpolator.addValueSource(new AbstractValueSource(false) {
+
+            @Override
+            public Object getValue(String expression, String expressionStartDelimiter, String expressionEndDelimiter) {
+                assertEquals("<expression>", expressionStartDelimiter);
+                assertEquals("</expression>", expressionEndDelimiter);
+                return expression;
+            }
+
+            @Override
+            public Object getValue(String expression) {
+                fail("This method is not supposed to be called");
+                return null;
+            }
+        });
+
+        assertEquals("test", interpolator.interpolate(src));
+    }
+
     @Test
     public void testSimpleSubstitution() throws InterpolationException {
         Properties p = new Properties();

src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java

@@ -19,12 +19,14 @@
 import java.util.HashMap;
 import java.util.Map;
 
+import org.codehaus.plexus.interpolation.AbstractValueSource;
 import org.codehaus.plexus.interpolation.InterpolationException;
 import org.codehaus.plexus.interpolation.MapBasedValueSource;
 import org.codehaus.plexus.interpolation.ValueSource;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class MultiDelimiterStringSearchInterpolatorTest {
 
@@ -119,4 +121,29 @@ public void testInterpolationWithMultipleEscapes3() throws InterpolationExceptio
 
         assertEquals("##${first} and #${second} and beer", result);
     }
+
+    @Test
+    public void testDelimitersPassedToValueSource() throws InterpolationException {
+        ValueSource vs = new AbstractValueSource(false) {
+
+            @Override
+            public Object getValue(String expression, String expressionStartDelimiter, String expressionEndDelimiter) {
+                assertEquals("#(", expressionStartDelimiter);
+                assertEquals(")", expressionEndDelimiter);
+                return expression;
+            }
+
+            @Override
+            public Object getValue(String expression) {
+                fail("This method is not supposed to be called");
+                return null;
+            }
+        };
+        MultiDelimiterStringSearchInterpolator interpolator = new MultiDelimiterStringSearchInterpolator() //
+                .withValueSource(vs) //
+                .escapeString("#");
+        interpolator.addDelimiterSpec("#(*)");
+
+        assertEquals("test", interpolator.interpolate("#(test)"));
+    }
 }