Add python coverage 3.7 to depot tools.

third_party/coverage/bytecode.py

Index: third_party/coverage/bytecode.py
diff --git a/third_party/coverage/bytecode.py b/third_party/coverage/bytecode.py
new file mode 100644
index 0000000000000000000000000000000000000000..85360638528e6bece33b1f5a1e4dd08e5c2ac3d0
--- /dev/null
+++ b/third_party/coverage/bytecode.py
@@ -0,0 +1,75 @@
+"""Bytecode manipulation for coverage.py"""
+
+import opcode, types
+
+from coverage.backward import byte_to_int
+
+class ByteCode(object):
+    """A single bytecode."""
+    def __init__(self):
+        # The offset of this bytecode in the code object.
+        self.offset = -1
+
+        # The opcode, defined in the `opcode` module.
+        self.op = -1
+
+        # The argument, a small integer, whose meaning depends on the opcode.
+        self.arg = -1
+
+        # The offset in the code object of the next bytecode.
+        self.next_offset = -1
+
+        # The offset to jump to.
+        self.jump_to = -1
+
+
+class ByteCodes(object):
+    """Iterator over byte codes in `code`.
+
+    Returns `ByteCode` objects.
+
+    """
+    # pylint: disable=R0924
+    def __init__(self, code):
+        self.code = code
+
+    def __getitem__(self, i):
+        return byte_to_int(self.code[i])
+
+    def __iter__(self):
+        offset = 0
+        while offset < len(self.code):
+            bc = ByteCode()
+            bc.op = self[offset]
+            bc.offset = offset
+
+            next_offset = offset+1
+            if bc.op >= opcode.HAVE_ARGUMENT:
+                bc.arg = self[offset+1] + 256*self[offset+2]
+                next_offset += 2
+
+                label = -1
+                if bc.op in opcode.hasjrel:
+                    label = next_offset + bc.arg
+                elif bc.op in opcode.hasjabs:
+                    label = bc.arg
+                bc.jump_to = label
+
+            bc.next_offset = offset = next_offset
+            yield bc
+
+
+class CodeObjects(object):
+    """Iterate over all the code objects in `code`."""
+    def __init__(self, code):
+        self.stack = [code]
+
+    def __iter__(self):
+        while self.stack:
+            # We're going to return the code object on the stack, but first
+            # push its children for later returning.
+            code = self.stack.pop()
+            for c in code.co_consts:
+                if isinstance(c, types.CodeType):
+                    self.stack.append(c)
+            yield code