Start libc++ python cleanup and consolidation.

Libc++ frequently creates and uses utilities written in python.
Currently there are python modules under both libcxx/test and
libcxx/util. My goal with these changes is to consolidate them
into a single package under libcxx/utils/libcxx.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294644 91177308-0d34-0410-b5e6-96231b3b80d8

utils/libcxx/sym_check/diff.py

@@ -0,0 +1,103 @@
+# -*- Python -*- vim: set syntax=python tabstop=4 expandtab cc=80:
+#===----------------------------------------------------------------------===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is dual licensed under the MIT and the University of Illinois Open
+# Source Licenses. See LICENSE.TXT for details.
+#
+#===----------------------------------------------------------------------===##
+"""
+diff - A set of functions for diff-ing two symbol lists.
+"""
+
+from libcxx.sym_check import util
+
+
+def _symbol_difference(lhs, rhs):
+    lhs_names = set((n['name'] for n in lhs))
+    rhs_names = set((n['name'] for n in rhs))
+    diff_names = lhs_names - rhs_names
+    return [n for n in lhs if n['name'] in diff_names]
+
+
+def _find_by_key(sym_list, k):
+    for sym in sym_list:
+        if sym['name'] == k:
+            return sym
+    return None
+
+
+def added_symbols(old, new):
+    return _symbol_difference(new, old)
+
+
+def removed_symbols(old, new):
+    return _symbol_difference(old, new)
+
+
+def changed_symbols(old, new):
+    changed = []
+    for old_sym in old:
+        if old_sym in new:
+            continue
+        new_sym = _find_by_key(new, old_sym['name'])
+        if (new_sym is not None and not new_sym in old
+                and cmp(old_sym, new_sym) != 0):
+            changed += [(old_sym, new_sym)]
+    return changed
+
+
+def diff(old, new):
+    added = added_symbols(old, new)
+    removed = removed_symbols(old, new)
+    changed = changed_symbols(old, new)
+    return added, removed, changed
+
+
+def report_diff(added_syms, removed_syms, changed_syms, names_only=False,
+                demangle=True):
+    def maybe_demangle(name):
+        return util.demangle_symbol(name) if demangle else name
+
+    report = ''
+    for sym in added_syms:
+        report += 'Symbol added: %s\n' % maybe_demangle(sym['name'])
+        if not names_only:
+            report += '    %s\n\n' % sym
+    if added_syms and names_only:
+        report += '\n'
+    for sym in removed_syms:
+        report += 'SYMBOL REMOVED: %s\n' % maybe_demangle(sym['name'])
+        if not names_only:
+            report += '    %s\n\n' % sym
+    if removed_syms and names_only:
+        report += '\n'
+    if not names_only:
+        for sym_pair in changed_syms:
+            old_sym, new_sym = sym_pair
+            old_str = '\n    OLD SYMBOL: %s' % old_sym
+            new_str = '\n    NEW SYMBOL: %s' % new_sym
+            report += ('SYMBOL CHANGED: %s%s%s\n\n' %
+                       (maybe_demangle(old_sym['name']),
+                        old_str, new_str))
+
+    added = bool(len(added_syms) != 0)
+    abi_break = bool(len(removed_syms))
+    if not names_only:
+        abi_break = abi_break or len(changed_syms)
+    if added or abi_break:
+        report += 'Summary\n'
+        report += '    Added:   %d\n' % len(added_syms)
+        report += '    Removed: %d\n' % len(removed_syms)
+        if not names_only:
+            report += '    Changed: %d\n' % len(changed_syms)
+        if not abi_break:
+            report += 'Symbols added.'
+        else:
+            report += 'ABI BREAKAGE: SYMBOLS ADDED OR REMOVED!'
+    else:
+        report += 'Symbols match.'
+    is_different = abi_break or bool(len(added_syms)) \
+                   or bool(len(changed_syms))
+    return report, abi_break, is_different