Integrate libuv into Wren.

- Add a script that downloads and compiles libuv.
- Hook that up to the Makefile so it pulls down libuv on build.
- Add a separate "vm" target that just builds the VM library and skips
  libuv.
- Link to libuv when compiling the CLI.
- Update the XCode project to link to libuv too.

Linux and Windows support isn't done yet, but it should be pretty
straightforward to add to the Python script.

script/libuv.py

@@ -0,0 +1,115 @@
+#!/usr/bin/env python
+
+# Downloads and compiles libuv.
+
+from __future__ import print_function
+
+import os
+import os.path
+import platform
+import shutil
+import subprocess
+import sys
+
+LIB_UV_VERSION = "v1.6.1"
+LIB_UV_DIR = "build/libuv"
+
+def ensure_dir(dir):
+  """Creates dir if not already there."""
+
+  if os.path.isdir(dir):
+    return
+
+  os.makedirs(dir)
+
+
+def download_libuv():
+  """Clones libuv into build/libuv and checks out the right version."""
+
+  # Delete it if already there so we ensure we get the correct version if the
+  # version number in this script changes.
+  if os.path.isdir(LIB_UV_DIR):
+    print("Cleaning output directory...")
+    shutil.rmtree(LIB_UV_DIR)
+
+  ensure_dir("build")
+
+  print("Cloning libuv...")
+  run([
+    "git", "clone", "--quiet", "--depth=1",
+    "https://github.com/libuv/libuv.git",
+    LIB_UV_DIR
+  ])
+
+  print("Getting tags...")
+  run([
+    "git", "fetch", "--quiet", "--depth=1", "--tags"
+  ], cwd=LIB_UV_DIR)
+
+  print("Checking out libuv " + LIB_UV_VERSION + "...")
+  run([
+    "git", "checkout", "--quiet", LIB_UV_VERSION
+  ], cwd=LIB_UV_DIR)
+
+  # TODO: Pin gyp to a known-good commit. Update a previously downloaded gyp
+  # if it doesn't match that commit.
+  print("Downloading gyp...")
+  run([
+    "git", "clone", "--quiet", "--depth=1",
+    "https://chromium.googlesource.com/external/gyp.git",
+    LIB_UV_DIR + "/build/gyp"
+  ])
+
+
+def build_libuv_mac():
+  # Create the XCode project.
+  run([
+    "python", LIB_UV_DIR + "/gyp_uv.py", "-f", "xcode"
+  ])
+
+  # Compile it.
+  # TODO: Support debug builds too.
+  run([
+    "xcodebuild",
+    "-ARCHS=\"x86_64\"",
+    "-project", LIB_UV_DIR + "/uv.xcodeproj",
+    "-configuration", "Release",
+    "-target", "All"
+  ])
+
+
+def build_libuv_linux():
+  # TODO: Implement me!
+  print("Building for Linux not implemented yet.")
+  sys.exit(1)
+
+
+def build_libuv_windows():
+  # TODO: Implement me!
+  print("Building for Windows not implemented yet.")
+  sys.exit(1)
+
+
+def build_libuv():
+  if platform.system() == "Darwin":
+    build_libuv_mac()
+  elif platform.system() == "Linux":
+    build_libuv_linux()
+  elif platform.system() == "Windows":
+    build_libuv_windows()
+  else:
+    print("Unsupported platform: " + platform.system())
+    sys.exit(1)
+
+
+def run(args, cwd=None):
+  """Spawn a process to invoke [args] and mute its output."""
+  subprocess.check_output(args, cwd=cwd, stderr=subprocess.STDOUT)
+
+
+def main():
+  download_libuv()
+  build_libuv()
+
+
+main()

script/wren.mk

@@ -98,19 +98,27 @@ CLI_OBJECTS  := $(addprefix $(BUILD_DIR)/cli/, $(notdir $(CLI_SOURCES:.c=.o)))
 VM_OBJECTS   := $(addprefix $(BUILD_DIR)/vm/, $(notdir $(VM_SOURCES:.c=.o)))
 TEST_OBJECTS := $(patsubst test/api/%.c, $(BUILD_DIR)/test/%.o, $(TEST_SOURCES))
 
+LIB_UV_DIR := build/libuv
+
 # Targets ---------------------------------------------------------------------
 
 # Builds the VM libraries and CLI interpreter.
-all: bin/$(WREN) lib/lib$(WREN).a lib/lib$(WREN).$(SHARED_EXT)
+all: vm cli
+
+# Builds just the VM libraries.
+vm: lib/lib$(WREN).a lib/lib$(WREN).$(SHARED_EXT)
+
+# Builds just the CLI interpreter.
+cli: bin/$(WREN)
 
 # Builds the API test executable.
 test: $(BUILD_DIR)/test/$(WREN)
 
 # Command-line interpreter.
-bin/$(WREN): $(CLI_OBJECTS) $(VM_OBJECTS)
+bin/$(WREN): $(CLI_OBJECTS) $(VM_OBJECTS) $(LIB_UV_DIR)/build/Release/libuv.a
 	@printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
 	@mkdir -p bin
-	@$(CC) $(CFLAGS) -o $@ $^ -lm
+	@$(CC) $(CFLAGS) -L$(LIB_UV_DIR)/build/Release -l uv -o $@ $^ -lm
 
 # Static library.
 lib/lib$(WREN).a: $(VM_OBJECTS)
@@ -134,7 +142,7 @@ $(BUILD_DIR)/test/$(WREN): $(TEST_OBJECTS) $(VM_OBJECTS) $(BUILD_DIR)/cli/io.o $
 $(BUILD_DIR)/cli/%.o: src/cli/%.c $(CLI_HEADERS) $(VM_HEADERS)
 	@printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
 	@mkdir -p $(BUILD_DIR)/cli
-	@$(CC) -c $(CFLAGS) -Isrc/include -o $@ $(FILE_FLAG) $<
+	@$(CC) -c $(CFLAGS) -Isrc/include -I$(LIB_UV_DIR)/include -o $@ $(FILE_FLAG) $<
 
 # VM object files.
 $(BUILD_DIR)/vm/%.o: src/vm/%.c $(VM_HEADERS)
@@ -148,4 +156,4 @@ $(BUILD_DIR)/test/%.o: test/api/%.c $(VM_HEADERS)
 	@mkdir -p $(dir $@)
 	@$(CC) -c $(CFLAGS) -Isrc/include -Isrc/cli -o $@ $(FILE_FLAG) $<
 
-.PHONY: all test
+.PHONY: all cli test vm