VPP-221 CLI auto-documentation infrastructure

As a step before Doxygen, extract CLI-related struct initializers
from the code and parse that into a summary of the CLI commands
available with the provided help text, such as it is. At the moment
this only renders this into an indexed Markdown file that Doxygen
then picks up but later we can use this information to enrich the
existing VLIB_CLI_COMMAND macro documentor as well as provide
runtime documentation to VPP that is stored on disk outside the
binary image.

Additionally support a comment block immediately prior to
VLIB_CLI_COMMAND CLI command definitions in the form /*? ... ?*/
that can be used to include long-form documentation without having
it compiled into VPP.

Examples of documenting CLI commands can be found in
vlib/vlib/unix/cli.c which, whilst not perfect, should provide a
starting point. Screen captures of sample output can be seen at
https://chrisy.flirble.org/vpp/doxy-cli-example.png and
https://chrisy.flirble.org/vpp/doxy-cli-index.png .

Next, shift the Doxygen root makefile targets to their own Makefile.
The primary reason for this is that the siphon targets do dependency
tracking which means it needs to generate those dependencies whenever
make is run; that is pointless if we're not going to generate any
documentation. This includes the package dependencies since they since
they sometimes unnecessarily interfere with the code build in some cases
at the moment; later we will look to building a Python venv to host the
Python modules we use.

One final remark: In future we may consider deprecating .long_help
in the VLIB_CLI_COMMAND structure entirely but add perhaps .usage_help.
.short_help would be reserved for a summary of the command function
and .usage_help provide the syntax of that command. These changes would
provide great semantic value to the automaticly generated CLI
documentation. I could also see having .long_help replaced by a
mechanism that reads it from disk at runtime with a rudimentary
Markdown/Doxygen filter so that we can use the same text that is used in
the published documentation.

Change-Id: I80d6fe349b47dce649fa77d21ffec0ddb45c7bbf
Signed-off-by: Chris Luke <chrisy@flirble.org>

1 files changed, 313 insertions, 0 deletions

diff --git a/doxygen/siphon_generate.py b/doxygen/siphon_generate.py
new file mode 100755
index 00000000000..457757b510c
--- /dev/null
+++ b/doxygen/siphon_generate.py
@@ -0,0 +1,313 @@
+#!/usr/bin/env python
+# Copyright (c) 2016 Comcast Cable Communications Management, LLC.
+#
+# 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.
+
+# Looks for preprocessor macros with struct initializers and siphons them
+# off into another file for later parsing; ostensibly to generate
+# documentation from struct initializer data.
+
+import os, sys, re, argparse, json
+
+DEFAULT_OUTPUT = "build-root/docs/siphons"
+DEFAULT_PREFIX = os.getcwd()
+
+ap = argparse.ArgumentParser()
+ap.add_argument("--output", '-o', metavar="directory", default=DEFAULT_OUTPUT,
+        help="Output directory for .siphon files [%s]" % DEFAULT_OUTPUT)
+ap.add_argument("--input-prefix", metavar="path", default=DEFAULT_PREFIX,
+        help="Prefix to strip from input pathnames [%s]" % DEFAULT_PREFIX)
+ap.add_argument("input", nargs='+', metavar="input_file",
+        help="Input C source files")
+args = ap.parse_args()
+
+"""Patterns that match the start of code blocks we want to siphon"""
+siphon_patterns = [
+    ( re.compile("(?P<m>VLIB_CLI_COMMAND)\s*[(](?P<name>[a-zA-Z0-9_]+)(,[^)]*)?[)]"), "clicmd" ),
+]
+
+"""Matches a siphon comment block start"""
+siphon_block_start = re.compile("^\s*/\*\?\s*(.*)$")
+
+"""Matches a siphon comment block stop"""
+siphon_block_stop = re.compile("^(.*)\s*\?\*/\s*$")
+
+"""Siphon block directive delimiter"""
+siphon_block_delimiter = "%%"
+
+"""Matches a siphon block directive such as '%clicmd:group_label Debug CLI%'"""
+siphon_block_directive = re.compile("(%s)\s*([a-zA-Z0-9_:]+)\s+(.*)\s*(%s)" % \
+        (siphon_block_delimiter, siphon_block_delimiter))
+
+"""Matches the start of an initializer block"""
+siphon_initializer = re.compile("\s*=")
+
+"""
+count open and close braces in str
+return (0, index) when braces were found and count becomes 0.
+index indicates the position at which the last closing brace was
+found.
+return (-1, -1) if a closing brace is found before any opening one.
+return (count, -1) if not all opening braces are closed, count is the
+current depth
+"""
+def count_braces(str, count=0, found=False):
+    for index in range(0, len(str)):
+        if str[index] == '{':
+            count += 1;
+            found = True
+        elif str[index] == '}':
+            if count == 0:
+                # means we never found an open brace
+                return (-1, -1)
+            count -= 1;
+
+        if count == 0 and found:
+            return (count, index)
+
+    return (count, -1)
+
+# Collated output for each siphon
+output = {}
+
+# Pre-process file names in case they indicate a file with
+# a list of files
+files = []
+for filename in args.input:
+    if filename.startswith('@'):
+        with open(filename[1:], 'r') as fp:
+            lines = fp.readlines()
+            for line in lines:
+                files.append(line.strip())
+            lines = None
+    else:
+        files.append(filename)
+
+# Iterate all the input files we've been given
+for filename in files:
+    # Strip the current directory off the start of the
+    # filename for brevity
+    if filename[0:len(args.input_prefix)] == args.input_prefix:
+        filename = filename[len(args.input_prefix):]
+        if filename[0] == "/":
+            filename = filename[1:]
+
+    # Work out the abbreviated directory name
+    directory = os.path.dirname(filename)
+    if directory[0:2] == "./":
+        directory = directory[2:]
+    elif directory[0:len(args.input_prefix)] == args.input_prefix:
+        directory = directory[len(args.input_prefix):]
+    if directory[0] == "/":
+    	directory = directory[1:]
+
+    # Open the file and explore its contents...
+    sys.stderr.write("Siphoning from %s...\n" % filename)
+    directives = {}
+    with open(filename) as fd:
+        siphon = None
+        close_siphon = None
+        siphon_block = ""
+        in_block = False
+        line_num = 0
+        siphon_line = 0
+
+        for line in fd:
+            line_num += 1
+            str = line[:-1] # filter \n
+
+            """See if there is a block directive and if so extract it"""
+            def process_block_directive(str, directives):
+                m = siphon_block_directive.search(str)
+                if m is not None:
+                    k = m.group(2)
+                    v = m.group(3).strip()
+                    directives[k] = v
+                    # Return only the parts we did not match
+                    return str[0:m.start(1)] + str[m.end(4):]
+
+                return str
+
+            def process_block_prefix(str):
+                if str.startswith(" * "):
+                    str = str[3:]
+                elif str == " *":
+                    str = ""
+                return str
+                
+            if not in_block:
+                # See if the line contains the start of a siphon doc block
+                m = siphon_block_start.search(str)
+                if m is not None:
+                    in_block = True
+                    t = m.group(1)
+
+                    # Now check if the block closes on the same line
+                    m = siphon_block_stop.search(t)
+                    if m is not None:
+                        t = m.group(1)
+                        in_block = False
+
+                    # Check for directives
+                    t = process_block_directive(t, directives)
+
+                    # Filter for normal comment prefixes
+                    t = process_block_prefix(t)
+
+                    # Add what is left
+                    siphon_block += t
+
+                    # Skip to next line
+                    continue
+
+            else:
+                # Check to see if we have an end block marker
+                m = siphon_block_stop.search(str)
+                if m is not None:
+                    in_block = False
+                    t = m.group(1)
+                else:
+                    t = str
+
+                # Check for directives
+                t = process_block_directive(t, directives)
+
+                # Filter for normal comment prefixes
+                t = process_block_prefix(t)
+
+                # Add what is left
+                siphon_block += t + "\n"
+
+                # Skip to next line
+                continue
+
+
+            if siphon is None:
+                # Look for blocks we need to siphon
+                for p in siphon_patterns:
+                    if p[0].match(str):
+                        siphon = [ p[1], str + "\n", 0 ]
+                        siphon_line = line_num
+
+                        # see if we have an initializer
+                        m = siphon_initializer.search(str)
+                        if m is not None:
+                            # count the braces on this line
+                            (count, index) = count_braces(str[m.start():])
+                            siphon[2] = count
+                            # TODO - it's possible we have the initializer all on the first line
+                            # we should check for it, but also account for the possibility that
+                            # the open brace is on the next line
+                            #if count == 0:
+                            #    # braces balanced
+                            #    close_siphon = siphon
+                            #    siphon = None
+                        else:
+                            # no initializer: close the siphon right now
+                            close_siphon = siphon
+                            siphon = None
+            else:
+                # See if we should end the siphon here - do we have balanced
+                # braces?
+                (count, index) = count_braces(str, count=siphon[2], found=True)
+                if count == 0:
+                    # braces balanced - add the substring and close the siphon
+                    siphon[1] += str[:index+1] + ";\n"
+                    close_siphon = siphon
+                    siphon = None
+                else:
+                    # add the whole string, move on
+                    siphon[2] = count
+                    siphon[1] += str + "\n"
+
+            if close_siphon is not None:
+                # Write the siphoned contents to the right place
+                siphon_name = close_siphon[0]
+                if siphon_name not in output:
+                    output[siphon_name] = {
+                        "global": {},
+                        "items": [],
+                        "file": "%s/%s.siphon" % (args.output, close_siphon[0])
+                    }
+
+                # Copy directives for the file
+                details = {}
+                for key in directives:
+                    if ":" in key:
+                        (sn, label) = key.split(":")
+                        if sn == siphon_name:
+                            details[label] = directives[key]
+                    else:
+                        details[key] = directives[key]
+
+                # Copy details for this block
+                details['file'] = filename
+                details['line_start'] = siphon_line
+                details['line_end'] = line_num
+                details['siphon_block'] = siphon_block.strip()
+
+                # Some defaults
+                if "group" not in details:
+                    if "group_label" in details:
+                        # use the filename since group labels are mostly of file scope
+                        details['group'] = details['file']
+                    else:
+			details['group'] = directory
+
+                if "group_label" not in details:
+                    details['group_label'] = details['group']
+
+                details["block"] = close_siphon[1]
+
+                # Store the item
+                output[siphon_name]['items'].append(details)
+
+                # All done
+                close_siphon = None
+                siphon_block = ""
+
+        # Update globals
+        for key in directives.keys():
+            if ':' not in key:
+                continue
+
+            if filename.endswith("/dir.dox"):
+                # very special! use the parent directory name
+                l = directory
+            else:
+                l = filename
+
+            (sn, label) = key.split(":")
+
+            if sn not in output:
+                output[sn] = {}
+            if 'global' not in output[sn]:
+                output[sn]['global'] = {}
+            if l not in output[sn]['global']:
+                output[sn]['global'][l] = {}
+            if 'file' not in output[sn]:
+                output[sn]['file'] = "%s/%s.siphon" % (args.output, sn)
+            if 'items' not in output[sn]:
+                output[sn]['items'] = []
+
+            output[sn]['global'][l][label] = directives[key]
+
+
+# Write out the data
+for siphon in output.keys():
+    sys.stderr.write("Saving siphon %s...\n" % siphon)
+    s = output[siphon]
+    with open(s['file'], "a") as fp:
+        json.dump(s, fp, separators=(',', ': '), indent=4, sort_keys=True)
+
+# All done