Half-done huge refactoring aimed to unify support of various types of docstrings

* Introduce new entities: DocStringBuilder, DocStringProvider and DocStringUpdater
* StructuredDocString serves only as dumb parser and operates only on
the level of Substrings to preserve offsets

python/psi-api/src/com/jetbrains/python/toolbox/PyIndentUtil.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2000-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.jetbrains.python.toolbox;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author Mikhail Golubev
+ */
+public class PyIndentUtil {
+  private PyIndentUtil() {
+  }
+
+  public static int getLineIndentSize(@NotNull CharSequence line) {
+    return getLineIndent(line).length();
+  }
+
+  @NotNull
+  public static CharSequence getLineIndent(@NotNull CharSequence line) {
+    int stop;
+    for (stop = 0; stop < line.length(); stop++) {
+      final char c = line.charAt(stop);
+      if (c == ' ' || c == '\t') {
+        break;
+      }
+    }
+    return line.subSequence(0, stop);
+  }
+}