01-input.txt

"<Abc=def>"
	"Abc=def" tags #1->0

"<Abc=def=ghi>"
	"Abc=def=ghi" tags #2->0

"<Abc=def=ghi=jkl>"
	"Abc=def=ghi=jkl" tags #3->0

"<Abc=def=ghi=jkl=mno>"
	"Abc=def=ghi=jkl=mno" tags #4->0

02-grammar.cg3

# Base case with 2 tokens
SplitCohort (
	"<$1>"v "$3"v <mv-begin> * c->p
	"<$2>"v "$4"v <mv-end> * 2->1
	) ("<([^=]+)=([^=]+)>"r "([^<][^=]*)=([^=]+)"r) ;

# Split tail if there are 3+ tokens. Temporary MWE- marker.
SplitCohort (
	"<MWE-$1>"v "$3"v * c->p
	"<$2>"v "$4"v <mv-end> * 2->1
	) ("<((?:[^=]+=){2,})([^=]+)>"r "((?:[^<][^=]*=){2,})([^=]+)"r) ;

# Split middle tokens, repeating until 2 remain
SplitCohort Repeat (
	"<MWE-$1>"v "$3"v * c->p
	"<$2>"v "$4"v * 2->1
	) ("<MWE-((?:[^=]+=){2,})([^=]+)=>"r "((?:[^<][^=]*=){2,})([^=]+)="r) ;

# Final split. Removes MWE- marker.
SplitCohort (
	"<$1>"v "$3"v <mv-begin> * c->p
	"<$2>"v "$4"v * 2->1
	) ("<MWE-([^=]+)=([^=]+)=>"r "([^<][^=]*)=([^=]+)="r) ;

03-output.txt

; "<Abc=def>"
;	"Abc=def" tags SPLITCOHORT:2
"<Abc>"
	"Abc" <mv-begin> tags #1->0 SPLITCOHORT:2
"<def>"
	"def" <mv-end> tags #2->1 SPLITCOHORT:2

; "<Abc=def=ghi>"
;	"Abc=def=ghi" tags SPLITCOHORT:8
; "<MWE-Abc=def=>"
;	"Abc=def=" tags SPLITCOHORT:8 SPLITCOHORT:20
"<Abc>"
	"Abc" <mv-begin> tags #3->0 SPLITCOHORT:20
"<def>"
	"def" tags #4->3 SPLITCOHORT:20
"<ghi>"
	"ghi" <mv-end> tags #5->3 SPLITCOHORT:8

; "<Abc=def=ghi=jkl>"
;	"Abc=def=ghi=jkl" tags SPLITCOHORT:8
; "<MWE-Abc=def=ghi=>"
;	"Abc=def=ghi=" tags SPLITCOHORT:8 SPLITCOHORT:14
; "<MWE-Abc=def=>"
;	"Abc=def=" tags SPLITCOHORT:14 SPLITCOHORT:20
"<Abc>"
	"Abc" <mv-begin> tags #6->0 SPLITCOHORT:20
"<def>"
	"def" tags #7->6 SPLITCOHORT:20
"<ghi>"
	"ghi" tags #8->6 SPLITCOHORT:14
"<jkl>"
	"jkl" <mv-end> tags #9->6 SPLITCOHORT:8

; "<Abc=def=ghi=jkl=mno>"
;	"Abc=def=ghi=jkl=mno" tags SPLITCOHORT:8
; "<MWE-Abc=def=ghi=jkl=>"
;	"Abc=def=ghi=jkl=" tags SPLITCOHORT:8 SPLITCOHORT:14
; "<MWE-Abc=def=ghi=>"
;	"Abc=def=ghi=" tags SPLITCOHORT:14 SPLITCOHORT:14
; "<MWE-Abc=def=>"
;	"Abc=def=" tags SPLITCOHORT:14 SPLITCOHORT:20
"<Abc>"
	"Abc" <mv-begin> tags #10->0 SPLITCOHORT:20
"<def>"
	"def" tags #11->10 SPLITCOHORT:20
"<ghi>"
	"ghi" tags #12->10 SPLITCOHORT:14
"<jkl>"
	"jkl" tags #13->10 SPLITCOHORT:14
"<mno>"
	"mno" <mv-end> tags #14->10 SPLITCOHORT:8