Camera: Generate tag string info from XML

Change-Id: I5109a3c46a065fb2dce31482d4377c33aeb84176
diff --git a/camera/docs/metadata_helpers.py b/camera/docs/metadata_helpers.py
new file mode 100644
index 0000000..bcfa29e
--- /dev/null
+++ b/camera/docs/metadata_helpers.py
@@ -0,0 +1,245 @@
+#
+# Copyright (C) 2012 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+A set of helpers for rendering Mako templates with a Metadata model.
+"""
+
+import metadata_model
+
+_context_buf = None
+
+def _is_sec_or_ins(x):
+  return isinstance(x, metadata_model.Section) or    \
+         isinstance(x, metadata_model.InnerNamespace)
+
+##
+## Metadata Helpers
+##
+
+def find_all_sections(root):
+  """
+  Find all descendants that are Section or InnerNamespace instances.
+
+  Args:
+    root: a Metadata instance
+
+  Returns:
+    A list of Section/InnerNamespace instances
+
+  Remarks:
+    These are known as "sections" in the generated C code.
+  """
+  return root.find_all(_is_sec_or_ins)
+
+def find_parent_section(entry):
+  """
+  Find the closest ancestor that is either a Section or InnerNamespace.
+
+  Args:
+    entry: an Entry or Clone node
+
+  Returns:
+    An instance of Section or InnerNamespace
+  """
+  return entry.find_parent_first(_is_sec_or_ins)
+
+# find uniquely named entries (w/o recursing through inner namespaces)
+def find_unique_entries(node):
+  """
+  Find all uniquely named entries, without recursing through inner namespaces.
+
+  Args:
+    node: a Section or InnerNamespace instance
+
+  Yields:
+    A sequence of MergedEntry nodes representing an entry
+
+  Remarks:
+    This collapses multiple entries with the same fully qualified name into
+    one entry (e.g. if there are multiple entries in different kinds).
+  """
+  if not isinstance(node, metadata_model.Section) and    \
+     not isinstance(node, metadata_model.InnerNamespace):
+      raise TypeError("expected node to be a Section or InnerNamespace")
+
+  d = {}
+  # remove the 'kinds' from the path between sec and the closest entries
+  # then search the immediate children of the search path
+  search_path = isinstance(node, metadata_model.Section) and node.kinds \
+                or [node]
+  for i in search_path:
+      for entry in i.entries:
+          d[entry.name] = entry
+
+  for k,v in d.iteritems():
+      yield v.merge()
+
+def path_name(node):
+  """
+  Calculate a period-separated string path from the root to this element,
+  by joining the names of each node and excluding the Metadata/Kind nodes
+  from the path.
+
+  Args:
+    node: a Node instance
+
+  Returns:
+    A string path
+  """
+
+  isa = lambda x,y: isinstance(x, y)
+  fltr = lambda x: not isa(x, metadata_model.Metadata) and \
+                   not isa(x, metadata_model.Kind)
+
+  path = node.find_parents(fltr)
+  path = list(path)
+  path.reverse()
+  path.append(node)
+
+  return ".".join((i.name for i in path))
+
+##
+## Filters
+##
+
+# abcDef.xyz -> ABC_DEF_XYZ
+def csym(name):
+  """
+  Convert an entry name string into an uppercase C symbol.
+
+  Returns:
+    A string
+
+  Example:
+    csym('abcDef.xyz') == 'ABC_DEF_XYZ'
+  """
+  newstr = name
+  newstr = "".join([i.isupper() and ("_" + i) or i for i in newstr]).upper()
+  newstr = newstr.replace(".", "_")
+  return newstr
+
+# abcDef.xyz -> abc_def_xyz
+def csyml(name):
+  """
+  Convert an entry name string into a lowercase C symbol.
+
+  Returns:
+    A string
+
+  Example:
+    csyml('abcDef.xyz') == 'abc_def_xyz'
+  """
+  return csym(name).lower()
+
+# pad with spaces to make string len == size. add new line if too big
+def ljust(size, indent=4):
+  """
+  Creates a function that given a string will pad it with spaces to make
+  the string length == size. Adds a new line if the string was too big.
+
+  Args:
+    size: an integer representing how much spacing should be added
+    indent: an integer representing the initial indendation level
+
+  Returns:
+    A function that takes a string and returns a string.
+
+  Example:
+    ljust(8)("hello") == 'hello   '
+
+  Remarks:
+    Deprecated. Use pad instead since it works for non-first items in a
+    Mako template.
+  """
+  def inner(what):
+    newstr = what.ljust(size)
+    if len(newstr) > size:
+      return what + "\n" + "".ljust(indent + size)
+    else:
+      return newstr
+  return inner
+
+def _find_new_line():
+
+  if _context_buf is None:
+    raise ValueError("Context buffer was not set")
+
+  buf = _context_buf
+  x = -1 # since the first read is always ''
+  cur_pos = buf.tell()
+  while buf.tell() > 0 and buf.read(1) != '\n':
+    buf.seek(cur_pos - x)
+    x = x + 1
+
+  buf.seek(cur_pos)
+
+  return int(x)
+
+# Pad the string until the buffer reaches the desired column.
+# If string is too long, insert a new line with 'col' spaces instead
+def pad(col):
+  """
+  Create a function that given a string will pad it to the specified column col.
+  If the string overflows the column, put the string on a new line and pad it.
+
+  Args:
+    col: an integer specifying the column number
+
+  Returns:
+    A function that given a string will produce a padded string.
+
+  Example:
+    pad(8)("hello") == 'hello   '
+
+  Remarks:
+    This keeps track of the line written by Mako so far, so it will always
+    align to the column number correctly.
+  """
+  def inner(what):
+    wut = int(col)
+    current_col = _find_new_line()
+
+    if len(what) > wut - current_col:
+      return what + "\n".ljust(col)
+    else:
+      return what.ljust(wut - current_col)
+  return inner
+
+# int32 -> TYPE_INT32, byte -> TYPE_BYTE, etc. note that enum -> TYPE_INT32
+def ctype_enum(what):
+  """
+  Generate a camera_metadata_type_t symbol from a type string.
+
+  Args:
+    what: a type string
+
+  Returns:
+    A string representing the camera_metadata_type_t
+
+  Example:
+    ctype_enum('int32') == 'TYPE_INT32'
+    ctype_enum('int64') == 'TYPE_INT64'
+    ctype_enum('float') == 'TYPE_FLOAT'
+    ctype_enum('enum')  == 'TYPE_INT32'
+
+  Remarks:
+    An enum is coerced to an int32 since the rest of the camera_metadata
+    code doesn't support enums directly yet.
+  """
+  if what == 'enum':
+      return 'TYPE_INT32'
+  return 'TYPE_%s' %(what.upper())