Changed builld-llvm.py to use .json files

LLDB has many branches in a variety of repositories.
The build-script.py file is subtly different for each set.
This is unnecessary and causes merge headaches.

This patch makes build-llvm.py consult a directory full 
of .json files, each one of which matches a particular
branch using a regular expression.

This update to the patch introduces a FALLBACK file
whose contents take precedence if the current branch
could not be identified.  If the current branch could be
identified, FALLBACK is updated, allowing the user to
e.g. cut branches off of known branches and still have
the automatic checkout mechanism work.

It also documents all of this.

Differential revision: https://reviews.llvm.org/D30275

llvm-svn: 295922

1 files changed, 26 insertions, 31 deletions

diff --git a/lldb/scripts/Xcode/build-llvm.py b/lldb/scripts/Xcode/build-llvm.py
index 792f92558b4..36e491ebf06 100755
--- a/lldb/scripts/Xcode/build-llvm.py
+++ b/lldb/scripts/Xcode/build-llvm.py
@@ -6,6 +6,7 @@ import fnmatch
 import os
 import platform
 import re
+import repo
 import subprocess
 import sys
 
@@ -17,42 +18,36 @@ from lldbbuild import *
 def LLVM_HASH_INCLUDES_DIFFS():
     return False
 
-# The use of "x = "..."; return x" here is important because tooling looks for
-# it with regexps.  Only change how this works if you know what you are doing.
-
-
-def LLVM_REF():
-    llvm_ref = "master"
-    return llvm_ref
-
+# For use with Xcode-style builds
 
-def CLANG_REF():
-    clang_ref = "master"
-    return clang_ref
+def process_vcs(vcs):
+    return {
+        "svn": VCS.svn,
+        "git": VCS.git
+    }[vcs]
 
-# For use with Xcode-style builds
+def process_root(name):
+    return {
+        "llvm": llvm_source_path(),
+        "clang": clang_source_path(),
+        "ninja": ninja_source_path()
+    }[name]
 
+def process_repo(r):
+    return {
+        'name': r["name"],
+        'vcs': process_vcs(r["vcs"]),
+        'root': process_root(r["name"]),
+        'url': r["url"],
+        'ref': r["ref"]
+    }
 
 def XCODE_REPOSITORIES():
-    return [
-        {'name': "llvm",
-         'vcs': VCS.git,
-         'root': llvm_source_path(),
-         'url': "http://llvm.org/git/llvm.git",
-         'ref': LLVM_REF()},
-
-        {'name': "clang",
-         'vcs': VCS.git,
-         'root': clang_source_path(),
-         'url': "http://llvm.org/git/clang.git",
-         'ref': CLANG_REF()},
-
-        {'name': "ninja",
-         'vcs': VCS.git,
-         'root': ninja_source_path(),
-         'url': "https://github.com/ninja-build/ninja.git",
-         'ref': "master"}
-    ]
+    identifier = repo.identifier()
+    if identifier == None:
+        identifier = "<invalid>" # repo.find will just use the fallback file
+    set = repo.find(identifier)
+    return [process_repo(r) for r in set]
 
 
 def get_c_compiler():