[GR-11899] str.title function is not implemented.

Author: ppisl

graalpython/com.oracle.graal.python.test/src/tests/test_string.py

@@ -685,6 +685,30 @@ def test_isprintable(self):
         # self.assertFalse('\U000E0020'.isprintable())
 
 
+    def test_title(self):
+        self.checkequal(' Hello ', ' hello ', 'title')
+        self.checkequal('Hello ', 'hello ', 'title')
+        self.checkequal('Hello ', 'Hello ', 'title')
+        self.checkequal('Format This As Title String', "fOrMaT thIs aS titLe String", 'title')
+        self.checkequal('Format,This-As*Title;String', "fOrMaT,thIs-aS*titLe;String", 'title', )
+        self.checkequal('Getint', "getInt", 'title')
+        self.checkraises(TypeError, 'hello', 'title', 42)
+
+    def test_title_uni(self):
+        self.assertEqual('\U0001044F'.title(), '\U00010427')
+        self.assertEqual('\U0001044F\U0001044F'.title(),
+                         '\U00010427\U0001044F')
+        self.assertEqual('\U0001044F\U0001044F \U0001044F\U0001044F'.title(),
+                         '\U00010427\U0001044F \U00010427\U0001044F')
+        self.assertEqual('\U00010427\U0001044F \U00010427\U0001044F'.title(),
+                         '\U00010427\U0001044F \U00010427\U0001044F')
+        self.assertEqual('\U0001044F\U00010427 \U0001044F\U00010427'.title(),
+                         '\U00010427\U0001044F \U00010427\U0001044F')
+        self.assertEqual('X\U00010427x\U0001044F X\U00010427x\U0001044F'.title(),
+                         'X\U0001044Fx\U0001044F X\U0001044Fx\U0001044F')
+        self.assertEqual('fiNNISH'.title(), 'Finnish')
+        self.assertEqual('A\u03a3A'.title(), 'A\u03c3a')
+
 def test_same_id():
     empty_ids = set([id(str()) for i in range(100)])
     assert len(empty_ids) == 1

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/str/StringBuiltins.java

@@ -1539,6 +1539,71 @@ boolean doString(String self) {
         }
     }
 
+    @Builtin(name = "title", fixedNumOfPositionalArgs = 1)
+    @GenerateNodeFactory
+    @TypeSystemReference(PythonArithmeticTypes.class)
+    abstract static class TitleNode extends PythonUnaryBuiltinNode {
+
+        @Specialization
+        @TruffleBoundary
+        public String doTitle(String self) {
+            int[] codePoints = self.codePoints().toArray();
+            int len = codePoints.length;
+            boolean shouldBeLowerCase = false;
+            boolean translated;
+            StringBuilder converted = new StringBuilder();
+            for (int i = 0; i < len; i++) {
+                int ch = codePoints[i];
+                translated = false;
+                if (Character.isAlphabetic(ch)) {
+                    if (shouldBeLowerCase) {
+                        // Should be lower case
+                        if (Character.isUpperCase(ch)) {
+                            translated = true;
+                            if (ch < 256) {
+                                converted.append((char) Character.toLowerCase(ch));
+                            } else {
+                                String origPart = new String(Character.toChars(ch));
+                                String changedPart = origPart.toLowerCase();
+                                converted.append(changedPart);
+                            }
+                        }
+                    } else {
+                        // Should be upper case
+                        if (Character.isLowerCase(ch)) {
+                            translated = true;
+                            if (ch < 256) {
+                                converted.append((char) Character.toUpperCase(ch));
+                            } else {
+                                String origPart = new String(Character.toChars(ch));
+                                String changedPart = origPart.toUpperCase();
+                                if (origPart.length() < changedPart.length()) {
+                                    // the original char was mapped to more chars ->
+                                    // we need to make upper case just the first one
+                                    changedPart = doTitle(changedPart);
+                                }
+                                converted.append(changedPart);
+                            }
+                        }
+                    }
+                    // And this was a letter
+                    shouldBeLowerCase = true;
+                } else {
+                    // This was not a letter
+                    shouldBeLowerCase = false;
+                }
+                if (!translated) {
+                    if (ch < 256) {
+                        converted.append((char) ch);
+                    } else {
+                        converted.append(Character.toChars(ch));
+                    }
+                }
+            }
+            return converted.toString();
+        }
+    }
+
     @Builtin(name = __GETITEM__, fixedNumOfPositionalArgs = 2)
     @GenerateNodeFactory
     @TypeSystemReference(PythonArithmeticTypes.class)