#!/bin/awk -f

# scripts/dfn.awk - process a .dfn file

#

# last changed in libpng version 1.5.19 - August 21, 2014

#

# Copyright (c) 2013-2014 Glenn Randers-Pehrson

#

# This code is released under the libpng license.

# For conditions of distribution and use, see the disclaimer

# and license in png.h

# The output of this script is written to the file given by

# the variable 'out', which should be set on the command line.

# Error messages are printed to stdout and if any are printed

# the script will exit with error code 1.

BEGIN{

   out="/dev/null"       # as a flag

   out_count=0           # count of output lines

   err=0                 # set if an error occurred

   sort=0                # sort the output

   array[""]=""

}

# The output file must be specified before any input:

NR==1 && out == "/dev/null" {

   print "out=output.file must be given on the command line"

   # but continue without setting the error code; this allows the

   # script to be checked easily

}

# Output can be sorted; two lines are recognized

$1 == "PNG_DFN_START_SORT"{

   sort=0+$2

   next

}

$1 ~ /^PNG_DFN_END_SORT/{

   # Do a very simple, slow, sort; notice that blank lines won't be

   # output by this

   for (entry in array) {

      while (array[entry] != "") {

         key = entry

         value = array[key]

         array[key] = ""

         for (alt in array) {

            if (array[alt] != "" && alt < key) {

               array[key] = value

               value = array[alt]

               key = alt

               array[alt] = ""

            }

         }

         print value >out

      }

   }

   sort=0

   next

}

/^[^"]*PNG_DFN *".*"[^"]*$/{

   # A definition line, apparently correctly formatted; extract the

   # definition then replace any doubled "" that remain with a single

   # double quote.  Notice that the original doubled double quotes

   # may have been split by tokenization

   #

   # Sometimes GCC splits the PNG_DFN lines; we know this has happened

   # if the quotes aren't closed and must read another line.  In this

   # case it is essential to reject lines that start with '#' because those

   # are introduced #line directives.

   orig=$0

   line=$0

   lineno=FNR

   if (lineno == "") lineno=NR

   if (sub(/^[^"]*PNG_DFN *"/,"",line) != 1) {

	print "line", lineno ": processing failed:"

	print orig

	err=1

       next

   } else {

	++out_count

   }

   # Now examine quotes within the value:

   #

   #   @" - delete this and any following spaces

   #   "@ - delete this and any preceding spaces

   #   @' - replace this by a double quote

   #

   # This allows macro substitution by the C compiler thus:

   #

   #   #define first_name John

   #   #define last_name Smith

   #

   #	PNG_DFN"#define name @'@" first_name "@ @" last_name "@@'"

   #

   # Might get C preprocessed to:

   #

   #   PNG_DFN "#define foo @'@" John "@ @" Smith "@@'"

   #

   # Which this script reduces to:

   #

   #	#define name "John Smith"

   #

   while (1) {

      # While there is an @" remove it and the next "@

      if (line ~ /@"/) {

         if (line ~ /@".*"@/) {

            # Do this special case first to avoid swallowing extra spaces

            # before or after the @ stuff:

            if (!sub(/@" *"@/, "", line)) {

               # Ok, do it in pieces - there has to be a non-space between the

               # two.  NOTE: really weird things happen if a leading @" is

               # lost - the code will error out below (I believe).

               if (!sub(/@" */, "", line) || !sub(/ *"@/, "", line)) {

                  print "line", lineno, ": internal error:", orig

                  exit 1

               }

            }

         }

         # There is no matching "@.  Assume a split line

         else while (1) {

            if (getline nextline) {

               # If the line starts with '#' it is a preprocesor line directive

               # from cc -E; skip it:

               if (nextline !~ /^#/) {

                  line = line " " nextline

                  break

               }

            } else {

               # This is end-of-input - probably a missing "@ on the first line:

               print "line", lineno ": unbalanced @\" ... \"@ pair"

               err=1

               next

            }

         }

         # Keep going until all the @" have gone

         continue

      }

      # Attempt to remove a trailing " (not preceded by '@') - if this can

      # be done, stop now; if not assume a split line again

      if (sub(/"[^"]*$/, "", line))

         break

      # Read another line

      while (1) {

         if (getline nextline) {

            if (nextline !~ /^#/) {

               line = line " " nextline

               # Go back to stripping @" "@ pairs

               break

            }

         } else {

            print "line", lineno ": unterminated PNG_DFN string"

            err=1

            next

         }

      }

   }

   # Put any needed double quotes in (at the end, because these would otherwise

   # interfere with the processing above.)

   gsub(/@'/,"\"", line)

   # Remove any trailing spaces (not really required, but for

   # editorial consistency

   sub(/ *$/, "", line)

   # Remove trailing CR

   sub(/
$/, "", line)

   if (sort) {

      if (split(line, parts) < sort) {

         print "line", lineno ": missing sort field:", line

         err=1

      } else

         array[parts[sort]] = line

   }

   else

      print line >out

   next

}

/PNG_DFN/{

   print "line", NR, "incorrectly formatted PNG_DFN line:"

   print $0

   err = 1

}

END{

   if (out_count > 0 || err > 0)

	exit err

   print "no definition lines found"

   exit 1

}