#!/bin/bash

###################################################################################

#

# unifdef2.sh script

#

# Arguments:

#   featureset-tag - this names the feature set and is used to identify sections

#     in the in-file to be considered in the out-file

#   in-file - the input file. The file must contain at least one instance of

#     "ifdef <tag>" and "endif <tag>" bracketing some text

#   out-file - the output file to be written after applying the filtering

#

#   unifdef2.sh filters a file by including everything outside of ifdef-endif

#     brackets, and including only lines inside ifdef-endif brackets with the

#     given featureset tag. All other lines are filtered out.

#

#   Syntax of ifdef-endif pairs:

#     Bracketing lines is accomplished by using "#ifdef <tag>" and "#endif <tag>"

#     lines starting in the first colunm. There must be a single space between

#     the ifdef/endif keyword and the tag. The tag can be followed by whitespace

#     and then optional commenting text.

#     Tags can be made up of alphnumeric and underscore characters, for example,

#     "opa10", "opa11_2", etc.

#     Examples:

#     #ifdef opa10

#     

#     #endif opa10 # this can be comments, the pound sign is not necessary

#

#   Calling example: MakeTools/unifdef2.sh opa10 foo.sh.base foo.sh

#     This example calls the script on the input file "foo.sh.base", processing

#     the file looking for ifdef-endif bracketing pairs, and excluding all code

#     within those brackets except those bracketed by "#ifdef opa10".."#endif opa10"

#

###################################################################################

check_tag_syntax()

{

	ltag1=$1

	where="$2"

	rest=${ltag1//[A-Za-z0-9_]}

	if [ "$rest" != "" ]

	then

		echo ERROR: unifdef2.sh: invalid featureset \<$ltag1\> "$where"

		echo        featureset can only be alphanumeric and underscores

		rm -f .greps .greps1

		exit 1

	fi

}

# shut off globbing

set -f

if [ $# -ne 3 ]

then

	echo ERROR: unifdef2.sh: wrong number of arguments: $#

	echo Usage: unifdef2.sh featureset-tag in-file out-file

	exit 1

fi

featureset=$1

in_file=$2

out_file=$3

check_tag_syntax $featureset "on command line"

# check existence of in_file

if [ ! -f $in_file ]

then

	echo ERROR: unifdef2.sh: no such file $in_file

	exit 1

fi

# check that in_file and out_file are different

if [ "$in_file" = "$out_file" ]

then

	echo ERROR: unifdef2.sh: in-file must be different than out-file

	echo Usage: unifdef2.sh featureset-tag in-file out-file

	exit 1

fi

# parse for syntax - check ifdef and endif tags, ensure matching and no nesting

# first extract all #ifdef and #endif directives to make it run faster

# ... in the grep, record the line nu㏔ers as well, we will use in main loop below

grep -n "^#ifdef .*" $in_file > .greps1

grep -n "^#endif .*" $in_file >> .greps1

sort -g .greps1 > .greps # sort using line numbers with general-number-sort

rm -f .greps1

# check for:

#  - mismatched ifdef-endif pairs

#  - endif before ifdef

#  - nesting

outside_bracket=1

save_tag=

while read line

do

	if [ $outside_bracket = 1 ]

	then

		if echo $line | grep "#ifdef " > /dev/null

		then

			save_tag=$(echo $line | cut -d' ' -f 2 | cut -f1)

			check_tag_syntax $save_tag "in $in_file"

			outside_bracket=0

		elif echo $line | grep "#endif " > /dev/null

		then

			save_tag=$(echo $line | cut -d' ' -f 2 | cut -f1)

			check_tag_syntax $save_tag "in $in_file"

			echo ERROR: unifdef2.sh: endif tag before ifdef for $save_tag in $in_file

			exit 1

		fi

	else # inside bracket - look for endif for this tag

		if echo $line | grep "#endif $save_tag" > /dev/null

		then

			save_tag=

			outside_bracket=1

		elif echo $line | grep "#ifdef " > /dev/null

		then

			save_tag2=$(echo $line | cut -d' ' -f 2 | cut -f1)

			check_tag_syntax $save_tag2 "in $in_file"

			echo ERROR: unifdef2.sh: ifdef tag for $save_tag2 before endif for $save_tag in $in_file

			exit 1

		elif echo $line | grep "#endif " > /dev/null

		then

			save_tag2=$(echo $line | cut -d' ' -f 2 | cut -f1)

			check_tag_syntax $save_tag2 "in $in_file"

			echo ERROR: unifdef2.sh: endif tag for $save_tag2 inside bracket for $save_tag in $in_file

			exit 1

		fi

	fi

done < .greps

if [ $outside_bracket = 0 ]

then

	echo ERROR: unifdef2.sh: no endif for ifdef for $save_tag in $in_file

	exit 1

fi

#

# now filter the file to create the out file

#

# Set writing to 1 (write everything except what is inside other ifdefs)

# Set line number to 1

#

# Loop through lines in in_file:

#   read a line

#   if the line number matches an ifdef/endif directive

#     grab tag and directive from line

#     if directive is ifdef

#       if tag does not match featureset

#         set writing to 0 (filter out this stuff)

#     else (directive is endif)

#       if tag does not match featureset

#         set writing to 1 (start writing again, "filter out" bracket is closed)

#   else (not a directive, just a normal line)

#     if writing is 1, write line to out_file

#   increment line number

#

> $out_file

chmod --reference=$in_file $out_file		# match permissions of in-file

writing=1

line_number=1

while IFS= read -r line

do

	# is line_number in .greps?

	if grep -w $line_number .greps > /dev/null

	then

		ltag=$(grep -w $line_number .greps|cut -f2 -d' '|cut -f1)

		ldirective=$(grep -w $line_number .greps | cut -d' ' -f1 | cut -d# -f2)

		if [ "$ldirective" = "ifdef" ]

		then

			if [ "$ltag" != "$featureset" ]

			then

				writing=0

			fi

		else # it is endif

			if [ "$ltag" != "$featureset" ]

			then

				writing=1

			fi

		fi

	elif [ $writing -eq 1 ]

	then

		echo "$line" >> $out_file

	fi

	line_number=$((line_number+1))

done < $in_file

rm -f .greps

exit 0