Merge pull request #124 from seart-group/language/state

lib/ch_usi_si_seart_treesitter_Language.cc

@@ -565,3 +565,13 @@ JNIEXPORT jobject JNICALL Java_ch_usi_si_seart_treesitter_Language_iterator(
     thisObject
   );
 }
+
+JNIEXPORT jint JNICALL Java_ch_usi_si_seart_treesitter_Language_nextState(
+  JNIEnv* env, jclass self, jlong id, jint state, jint symbol) {
+  if (id == (jlong)ch_usi_si_seart_treesitter_Language_INVALID) return (jint)(-1);
+  return (jint)ts_language_next_state(
+    (const TSLanguage*)id,
+    (TSStateId)state,
+    (TSSymbol)symbol
+  );
+}

src/main/java/ch/usi/si/seart/treesitter/Language.java

@@ -618,6 +618,32 @@ public static void validate(@NotNull Language language) {
      */
     public native LookaheadIterator iterator(int state);
 
+    /**
+     * Obtain the next language parse state for a given {@link Node}.
+     * <p>
+     * Combine this with lookahead iterators to generate completion
+     * suggestions or valid symbols in {@code ERROR} nodes.
+     *
+     * @param node the node
+     * @return the next parse state
+     * @throws NullPointerException if {@code node} is null
+     * @throws IllegalArgumentException if this language
+     * was not used to parse the node and its syntax tree
+     * @since 1.12.0
+     */
+    public int nextState(@NotNull Node node) {
+        Objects.requireNonNull(node, "Node must not be null!");
+        Language language = node.getLanguage();
+        if (!this.equals(language)) throw new IllegalArgumentException(
+                "Node language does not match the language of this instance!"
+        );
+        int state = node.getParseState();
+        Symbol symbol = node.getGrammarSymbol();
+        return nextState(id, state, symbol.getId());
+    }
+
+    private static native int nextState(long id, int state, int symbol);
+
     @Generated
     @SuppressWarnings("unused")
     public int getTotalSymbols() {

src/test/java/ch/usi/si/seart/treesitter/LanguageTest.java

@@ -1,6 +1,8 @@
 package ch.usi.si.seart.treesitter;
 
+import lombok.Cleanup;
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -100,4 +102,21 @@ public Stream<? extends Arguments> provideArguments(ExtensionContext extensionCo
     void testAssociatedWithThrows(Class<Throwable> throwableType, Path path) {
         Assertions.assertThrows(throwableType, () -> Language.associatedWith(path));
     }
+
+    @Test
+    void testNextState() {
+        Language language = Language.PYTHON;
+        @Cleanup Parser parser = Parser.getFor(language);
+        @Cleanup Tree tree = parser.parse("pass");
+        Node root = tree.getRootNode();
+        Assertions.assertEquals(0, language.nextState(root));
+    }
+
+    @Test
+    void testNextStateThrows() {
+        Assertions.assertThrows(NullPointerException.class, () -> Language.JAVA.nextState(null));
+        Assertions.assertThrows(NullPointerException.class, () -> Language._INVALID_.nextState(null));
+        Assertions.assertThrows(IllegalArgumentException.class, () -> Language.JAVA.nextState(empty));
+        Assertions.assertThrows(IllegalArgumentException.class, () -> Language._INVALID_.nextState(empty));
+    }
 }