1 files changed, 105 insertions, 0 deletions
diff --git a/Lib/idlelib/autoexpand.py b/Lib/idlelib/autoexpand.py
new file mode 100644
index 0000000000..6b46bee69c
--- /dev/null
+++ b/Lib/idlelib/autoexpand.py
@@ -0,0 +1,105 @@
+'''Complete the current word before the cursor with words in the editor.
+
+Each menu selection or shortcut key selection replaces the word with a
+different word with the same prefix. The search for matches begins
+before the target and moves toward the top of the editor. It then starts
+after the cursor and moves down. It then returns to the original word and
+the cycle starts again.
+
+Changing the current text line or leaving the cursor in a different
+place before requesting the next selection causes AutoExpand to reset
+its state.
+
+This is an extension file and there is only one instance of AutoExpand.
+'''
+import re
+import string
+
+###$ event <<expand-word>>
+###$ win <Alt-slash>
+###$ unix <Alt-slash>
+
+class AutoExpand:
+
+    menudefs = [
+        ('edit', [
+            ('E_xpand Word', '<<expand-word>>'),
+         ]),
+    ]
+
+    wordchars = string.ascii_letters + string.digits + "_"
+
+    def __init__(self, editwin):
+        self.text = editwin.text
+        self.bell = self.text.bell
+        self.state = None
+
+    def expand_word_event(self, event):
+        "Replace the current word with the next expansion."
+        curinsert = self.text.index("insert")
+        curline = self.text.get("insert linestart", "insert lineend")
+        if not self.state:
+            words = self.getwords()
+            index = 0
+        else:
+            words, index, insert, line = self.state
+            if insert != curinsert or line != curline:
+                words = self.getwords()
+                index = 0
+        if not words:
+            self.bell()
+            return "break"
+        word = self.getprevword()
+        self.text.delete("insert - %d chars" % len(word), "insert")
+        newword = words[index]
+        index = (index + 1) % len(words)
+        if index == 0:
+            self.bell()            # Warn we cycled around
+        self.text.insert("insert", newword)
+        curinsert = self.text.index("insert")
+        curline = self.text.get("insert linestart", "insert lineend")
+        self.state = words, index, curinsert, curline
+        return "break"
+
+    def getwords(self):
+        "Return a list of words that match the prefix before the cursor."
+        word = self.getprevword()
+        if not word:
+            return []
+        before = self.text.get("1.0", "insert wordstart")
+        wbefore = re.findall(r"\b" + word + r"\w+\b", before)
+        del before
+        after = self.text.get("insert wordend", "end")
+        wafter = re.findall(r"\b" + word + r"\w+\b", after)
+        del after
+        if not wbefore and not wafter:
+            return []
+        words = []
+        dict = {}
+        # search backwards through words before
+        wbefore.reverse()
+        for w in wbefore:
+            if dict.get(w):
+                continue
+            words.append(w)
+            dict[w] = w
+        # search onwards through words after
+        for w in wafter:
+            if dict.get(w):
+                continue
+            words.append(w)
+            dict[w] = w
+        words.append(word)
+        return words
+
+    def getprevword(self):
+        "Return the word prefix before the cursor."
+        line = self.text.get("insert linestart", "insert")
+        i = len(line)
+        while i > 0 and line[i-1] in self.wordchars:
+            i = i-1
+        return line[i:]
+
+if __name__ == '__main__':
+    import unittest
+    unittest.main('idlelib.idle_test.test_autoexpand', verbosity=2)