regex101: Basic grammar for regex matching of simplistic Makefiles

1st Alternative(?P<assign_op>(\:|\!|\?)?=)

Group assign_op(?P<assign_op>(\:|\!|\?)?=)

Group 2(\:|\!|\?)?

?repeats the group contents below at most once:

1st Alternative\:

\:the literal : (58₁₀ / 72₈ / 3A₁₆)

2nd Alternative\!

\!the literal ! (33₁₀ / 41₈ / 21₁₆)

3rd Alternative\?

\?the literal ? (63₁₀ / 77₈ / 3F₁₆)

=the literal = (61₁₀ / 75₈ / 3D₁₆)

2nd Alternative(?P<token_subst>$|%(\<\@))

Group token_subst(?P<token_subst>$|%(\<\@))

1st Alternative$

$end of line

2nd Alternative%(\<\@)

%the literal % (37₁₀ / 45₈ / 25₁₆)

Group 4(\<\@)

\<the literal < (60₁₀ / 74₈ / 3C₁₆)

\@the literal @ (64₁₀ / 100₈ / 40₁₆)

3rd Alternative(?P<token_ident>[\w\d\.\,]+)

Group token_ident(?P<token_ident>[\w\d\.\,]+)

Character Class[\w\d\.\,]+

+matches at least one character from the set below:

\wa Unicode word character

\da Unicode decimal digit

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\,the literal , (44₁₀ / 54₈ / 2C₁₆)

4th Alternative(?P<target_name_match>%\.?)

Group target_name_match(?P<target_name_match>%\.?)

%the literal % (37₁₀ / 45₈ / 25₁₆)

\.?optionally matches the literal . (46₁₀ / 56₈ / 2E₁₆)

5th Alternative(?P<token_rule_sep>[:])

Group token_rule_sep(?P<token_rule_sep>[:])

Character Class[:]

:the literal : (58₁₀ / 72₈ / 3A₁₆)

6th Alternative(?P<incr_op>\n)

Group incr_op(?P<incr_op>\n)

\na line-feed (newline) character (ASCII 10)

7th Alternative(?P<line_end>\n)

Group line_end(?P<line_end>\n)

\na line-feed (newline) character (ASCII 10)

8th Alternative(?P<comment_op>#[.*]+$)

Group comment_op(?P<comment_op>#[.*]+$)

#the literal # (35₁₀ / 43₈ / 23₁₆)

Character Class[.*]+

$end of line

9th Alternative(?P<adjust_parser>[\$%\s\t\:])

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

(?P<assign_op>(\:|\!|\?)?=)|(?P<token_subst>$|%(\<\@))|(?P<token_ident>[\w\d\.\,]+)|(?P<target_name_match>%\.?)|(?P<token_rule_sep>[:])|(?P<incr_op>\n)|(?P<line_end>\n)|(?P<comment_op>#[.*]+$)|(?P<adjust_parser>[\$%\s\t\:])

New

CC           := nasm
BOOT_REQ     := text.o
FREELDR_SRCS := freeldr.c
IMG_NAME     := boot.img

TEXT_SECTION := 7c00

# UFS2, ZFS and/or RAW
FILESYSTEMS :=
CPU_FLAGS   := PAE
SDK_FLAGS   :=
VERSION     := "1.00.00"

%.o:
    $(ASM) ${SDK_FLAGS} -f bin -o $@ $(patsubst %.bin,%.asm,$@))

${IMG_NAME}:
    $(BOOT_REQ) $(FREELDR_SRCS:.c=.o)