Add completion for constant array 'length' attribute (#1119)

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/languageserver/requests/GetCompletions.java

@@ -145,6 +145,8 @@ private void calculateCompletions(List<CompletionItem> completions) {
 
             WurstType leftType = e.getLeft().attrTyp();
 
+            addArrayLengthCompletion(completions, e, leftType);
+
             if (leftType instanceof WurstTypeNamedScope) {
                 WurstTypeNamedScope ct = (WurstTypeNamedScope) leftType;
                 for (DefLink nameLink : ct.nameLinks().values()) {
@@ -229,6 +231,28 @@ private void calculateCompletions(List<CompletionItem> completions) {
 
     }
 
+    private void addArrayLengthCompletion(List<CompletionItem> completions, ExprMember member, WurstType leftType) {
+        boolean hasConstArrayInitializer = false;
+        if (member.getLeft() instanceof NameRef) {
+            NameDef nameDef = ((NameRef) member.getLeft()).tryGetNameDef();
+            if (nameDef instanceof GlobalOrLocalVarDef) {
+                GlobalOrLocalVarDef varDef = (GlobalOrLocalVarDef) nameDef;
+                hasConstArrayInitializer = varDef.getInitialExpr() instanceof ArrayInitializer;
+            }
+        }
+
+        if (!hasConstArrayInitializer || !isSuitableCompletion("length")) {
+            return;
+        }
+
+        CompletionItem completion = new CompletionItem("length");
+        completion.setKind(CompletionItemKind.Property);
+        completion.setDetail("int length");
+        completion.setInsertText("length");
+        completion.setSortText(ratingToString(calculateRating("length", WurstTypeInt.instance())));
+        completions.add(completion);
+    }
+
     private void addKeywordCompletions(List<CompletionItem> completions) {
         for (String keyword : WurstKeywords.KEYWORDS) {
             if (keyword.startsWith(alreadyEntered)) {

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/AutoCompleteTests.java

@@ -14,8 +14,7 @@
 import java.util.List;
 import java.util.stream.Collectors;
 
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertFalse;
+import static org.testng.Assert.*;
 
 /**
  * tests the autocomplete functionality.
@@ -416,6 +415,42 @@ public void testInnerClasses() {
         testCompletions(testData, "Banana", "Blue", "Boris");
     }
 
+    @Test
+    public void constantArrayLengthCompletion() {
+        CompletionTestData testData = input(
+            "package test",
+            "const ints = [1, 2, 3]",
+            "init",
+            "    ints.|",
+            "endpackage"
+        );
+
+        CompletionList completions = calculateCompletions(testData);
+
+        assertTrue(
+            completions.getItems().stream().anyMatch(c -> "length".equals(c.getLabel())),
+            "Expected to suggest the synthetic array length property"
+        );
+    }
+
+    @Test
+    public void nonConstantArrayDoesNotSuggestLength() {
+        CompletionTestData testData = input(
+            "package test",
+            "int array ints",
+            "init",
+            "    ints.|",
+            "endpackage"
+        );
+
+        CompletionList completions = calculateCompletions(testData);
+
+        assertFalse(
+            completions.getItems().stream().anyMatch(c -> "length".equals(c.getLabel())),
+            "Did not expect to suggest length for non-constant arrays"
+        );
+    }
+
 	private void testCompletions(CompletionTestData testData, String... expectedCompletions) {
         testCompletions(testData, Arrays.asList(expectedCompletions));
     }