Check in signature generator

diff --git a/devscripts/youtube_genalgo.py b/devscripts/youtube_genalgo.py
new file mode 100644 (file)
index 0000000..01583e4
--- /dev/null
+++ b/devscripts/youtube_genalgo.py
@@ -0,0 +1,76 @@
+#!/usr/bin/env python
+
+# Generate youtube signature algorithm from test cases
+
+import sys
+
+tests = [
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[]}|:;?/>.<",
+     "J:|}][{=+-_)(*&;%$#@>MNBVCXZASDFGH^KLPOIUYTREWQ0987654321mnbvcxzasdfghrklpoiuytej"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$^&*()_-+={[]}|:;?/>.<",
+     "!?;:|}][{=+-_)(*&^$#@/MNBVCXZASqFGHJKLPOIUYTREWQ0987654321mnbvcxzasdfghjklpoiuytr"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|};?/>.<",
+     "ertyuioplkjhgfdqazxcvbnm1234567890QWERT}UIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[|/;?Y"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[};?/>.<",
+     "{>/?;}[.=+-_)(*&^%$#@!MqBVCXZASDFwHJKLPOIUYTREWQ0987654321mnbvcxzasdfghjklpoiuytr"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!@#$%^&*()_-+={[};?>.<",
+     "<.>?;}[{=+-_)(*&^%$#@!MNBVCXZASDFGHJKLPOIUYTREWe098765432rmnbvcxzasdfghjklpoiuyt1"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKJHGFDSAZXCVBNM!#$%^&*()_+={[};?/>.<",
+     "D.>/?;}[{=+_)(*&^%$#!MNBVCXeAS<FGHJKLPOIUYTREWZ0987654321mnbvcxzasdfghjklpoiuytrQ"),
+    ("qwertyuioplkjhgfdsazxcvbnm1234567890QWERTYUIOPLKHGFDSAZXCVBNM!@#$%^&*(-+={[};?/>.<",
+     "Q>/?;}[{=+-(*<^%$#@!MNBVCXZASDFGHKLPOIUY8REWT0q&7654321mnbvcxzasdfghjklpoiuytrew9"),
+]
+
+def find_matching(wrong, right):
+    idxs = [wrong.index(c) for c in right]
+    return compress(idxs)
+    return ('s[%d]' % i for i in idxs)
+
+def compress(idxs):
+    def _genslice(start, end, step):
+        starts = '' if start == 0 else str(start)
+        ends = ':%d' % (end+step)
+        steps = '' if step == 1 else (':%d' % step)
+        return 's[%s%s%s]' % (starts, ends, steps)
+
+    step = None
+    for i, prev in zip(idxs[1:], idxs[:-1]):
+        if step is not None:
+            if i - prev == step:
+                continue
+            yield _genslice(start, prev, step)
+            step = None
+            continue
+        if i - prev in [-1, 1]:
+            step = i - prev
+            start = prev
+            continue
+        else:
+            yield 's[%d]' % prev
+    if step is None:
+        yield 's[%d]' % i
+    else:
+        yield _genslice(start, i, step)
+
+def _assert_compress(inp, exp):
+    res = list(compress(inp))
+    if res != exp:
+        print('Got %r, expected %r' % (res, exp))
+        assert res == exp
+_assert_compress([0,2,4,6], ['s[0]', 's[2]', 's[4]', 's[6]'])
+_assert_compress([0,1,2,4,6,7], ['s[:3]', 's[4]', 's[6:8]'])
+_assert_compress([8,0,1,2,4,7,6,9], ['s[8]', 's[:3]', 's[4]', 's[7:5:-1]', 's[9]'])
+
+def gen(wrong, right, indent):
+    code = ' + '.join(find_matching(wrong, right))
+    return 'if len(s) == %d:\n%s    return %s\n' % (len(wrong), indent, code)
+
+def genall(tests):
+    indent = ' ' * 8
+    return indent + (indent + 'el').join(gen(wrong, right, indent) for wrong,right in tests)
+
+def main():
+    print(genall(tests))
+
+if __name__ == '__main__':
+    main()