Before/after options for reorder verb (#510)

* mlr reorder -b/-a
* go test data
* c impl

c/mapping/mapper_reorder.c

@@ -2,21 +2,28 @@
 #include "containers/lrec.h"
 #include "containers/sllv.h"
 #include "containers/hss.h"
+#include "containers/mixutil.h"
 #include "mapping/mappers.h"
 #include "cli/argparse.h"
 
 typedef struct _mapper_reorder_state_t {
 	ap_state_t* pargp;
 	slls_t* pfield_name_list;
-	int     put_at_end;
+	hss_t* pfield_name_set;
+	char* before_field_name;
+	char* after_field_name;
 } mapper_reorder_state_t;
 
 static void      mapper_reorder_usage(FILE* o, char* argv0, char* verb);
 static mapper_t* mapper_reorder_parse_cli(int* pargi, int argc, char** argv,
 	cli_reader_opts_t* _, cli_writer_opts_t* __);
-static mapper_t* mapper_reorder_alloc(ap_state_t* pargp, slls_t* pfield_name_list, int put_at_end);
+static mapper_t* mapper_reorder_alloc(ap_state_t* pargp, slls_t* pfield_name_list,
+	int put_at_end, char* before_field_name, char* after_field_name);
 static void      mapper_reorder_free(mapper_t* pmapper, context_t* _);
-static sllv_t*   mapper_reorder_process(lrec_t* pinrec, context_t* pctx, void* pvstate);
+static sllv_t*   mapper_reorder_to_start(lrec_t* pinrec, context_t* pctx, void* pvstate);
+static sllv_t*   mapper_reorder_to_end(lrec_t* pinrec, context_t* pctx, void* pvstate);
+static sllv_t*   mapper_reorder_before(lrec_t* pinrec, context_t* pctx, void* pvstate);
+static sllv_t*   mapper_reorder_after(lrec_t* pinrec, context_t* pctx, void* pvstate);
 
 // ----------------------------------------------------------------
 mapper_setup_t mapper_reorder_setup = {
@@ -29,28 +36,36 @@ mapper_setup_t mapper_reorder_setup = {
 // ----------------------------------------------------------------
 static void mapper_reorder_usage(FILE* o, char* argv0, char* verb) {
 	fprintf(o, "Usage: %s %s [options]\n", argv0, verb);
-	fprintf(o, "-f {a,b,c}   Field names to reorder.\n");
-	fprintf(o, "-e           Put specified field names at record end: default is to put\n");
-	fprintf(o, "             them at record start.\n");
+	fprintf(o, "-f {a,b,c} Field names to reorder.\n");
+	fprintf(o, "-e         Put specified field names at record end: default is to put\n");
+	fprintf(o, "           them at record start.\n");
+	fprintf(o, "-b {x}     Put field names specified with -f before field name specified by {x},\n");
+	fprintf(o, "           if any. If {x} isn't present in a given record, the specified fields\n");
+	fprintf(o, "           will not be moved.\n");
+	fprintf(o, "-a {x}     Put field names specified with -f after field name specified by {x},\n");
+	fprintf(o, "           if any. If {x} isn't present in a given record, the specified fields\n");
+	fprintf(o, "           will not be moved.\n");
 	fprintf(o, "Examples:\n");
-	fprintf(o, "%s %s    -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"a=1,b=2,d=4,c=3\".\n",
-		argv0, verb);
-	fprintf(o, "%s %s -e -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"d=4,c=3,a=1,b=2\".\n",
-		argv0, verb);
+	fprintf(o, "%s %s    -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"a=1,b=2,d=4,c=3\".\n", argv0, verb);
+	fprintf(o, "%s %s -e -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"d=4,c=3,a=1,b=2\".\n", argv0, verb);
 }
 
 // ----------------------------------------------------------------
 static mapper_t* mapper_reorder_parse_cli(int* pargi, int argc, char** argv,
 	cli_reader_opts_t* _, cli_writer_opts_t* __)
 {
-	slls_t* pfield_name_list = NULL;
-	int     put_at_end       = FALSE;
+	slls_t* pfield_name_list  = NULL;
+	int     put_at_end        = FALSE;
+	char*   before_field_name = NULL;
+	char*   after_field_name  = NULL;
 
 	char* verb = argv[(*pargi)++];
 
 	ap_state_t* pstate = ap_alloc();
 	ap_define_string_list_flag(pstate, "-f", &pfield_name_list);
 	ap_define_true_flag(pstate, "-e", &put_at_end);
+	ap_define_string_flag(pstate, "-b", &before_field_name);
+	ap_define_string_flag(pstate, "-a", &after_field_name);
 
 	if (!ap_parse(pstate, verb, pargi, argc, argv)) {
 		mapper_reorder_usage(stderr, argv[0], verb);
@@ -62,50 +77,169 @@ static mapper_t* mapper_reorder_parse_cli(int* pargi, int argc, char** argv,
 		return NULL;
 	}
 
-	return mapper_reorder_alloc(pstate, pfield_name_list, put_at_end);
+	return mapper_reorder_alloc(pstate, pfield_name_list, put_at_end, before_field_name, after_field_name);
 }
 
 // ----------------------------------------------------------------
-static mapper_t* mapper_reorder_alloc(ap_state_t* pargp, slls_t* pfield_name_list, int put_at_end) {
+static mapper_t* mapper_reorder_alloc(ap_state_t* pargp, slls_t* pfield_name_list,
+	int put_at_end, char* before_field_name, char* after_field_name)
+{
 	mapper_t* pmapper = mlr_malloc_or_die(sizeof(mapper_t));
 
 	mapper_reorder_state_t* pstate = mlr_malloc_or_die(sizeof(mapper_reorder_state_t));
 	pstate->pargp = pargp;
-	pstate->pfield_name_list = pfield_name_list;
-	pstate->put_at_end = put_at_end;
-	if (!put_at_end)
-		slls_reverse(pstate->pfield_name_list);
+	pstate->pfield_name_list  = pfield_name_list;
+	pstate->pfield_name_set = hss_from_slls(pfield_name_list);
+	pstate->before_field_name = before_field_name;
+	pstate->after_field_name  = after_field_name;
 
-	pmapper->pvstate       = (void*)pstate;
-	pmapper->pprocess_func = mapper_reorder_process;
-	pmapper->pfree_func    = mapper_reorder_free;
+	pmapper->pvstate = (void*)pstate;
+
+	if (put_at_end) {
+		pmapper->pprocess_func = mapper_reorder_to_end;
+	} else if (before_field_name != NULL) {
+		pmapper->pprocess_func = mapper_reorder_before;
+	} else if (after_field_name != NULL) {
+		pmapper->pprocess_func = mapper_reorder_after;
+	} else {
+		pmapper->pprocess_func = mapper_reorder_to_start;
+		slls_reverse(pstate->pfield_name_list);
+	}
+	pmapper->pfree_func = mapper_reorder_free;
 
 	return pmapper;
 }
 
 static void mapper_reorder_free(mapper_t* pmapper, context_t* _) {
 	mapper_reorder_state_t* pstate = pmapper->pvstate;
-	if (pstate->pfield_name_list != NULL)
-		slls_free(pstate->pfield_name_list);
+	slls_free(pstate->pfield_name_list);
+	hss_free(pstate->pfield_name_set);
 	ap_free(pstate->pargp);
 	free(pstate);
 	free(pmapper);
 }
 
 // ----------------------------------------------------------------
-static sllv_t* mapper_reorder_process(lrec_t* pinrec, context_t* pctx, void* pvstate) {
+static sllv_t* mapper_reorder_to_start(lrec_t* pinrec, context_t* pctx, void* pvstate) {
 	mapper_reorder_state_t* pstate = (mapper_reorder_state_t*)pvstate;
 	if (pinrec != NULL) {
-		if (!pstate->put_at_end) {
-			// OK since the field-name list was reversed at construction time.
-			for (sllse_t* pe = pstate->pfield_name_list->phead; pe != NULL; pe = pe->pnext)
-				lrec_move_to_head(pinrec, pe->value);
-		} else {
-			for (sllse_t* pe = pstate->pfield_name_list->phead; pe != NULL; pe = pe->pnext)
-				lrec_move_to_tail(pinrec, pe->value);
+		// OK since the field-name list was reversed at construction time.
+		for (sllse_t* pe = pstate->pfield_name_list->phead; pe != NULL; pe = pe->pnext) {
+			lrec_move_to_head(pinrec, pe->value);
 		}
 		return sllv_single(pinrec);
 	} else {
 		return sllv_single(NULL);
 	}
 }
+
+// ----------------------------------------------------------------
+static sllv_t* mapper_reorder_to_end(lrec_t* pinrec, context_t* pctx, void* pvstate) {
+	mapper_reorder_state_t* pstate = (mapper_reorder_state_t*)pvstate;
+	if (pinrec != NULL) {
+		for (sllse_t* pe = pstate->pfield_name_list->phead; pe != NULL; pe = pe->pnext) {
+			lrec_move_to_tail(pinrec, pe->value);
+		}
+		return sllv_single(pinrec);
+	} else {
+		return sllv_single(NULL);
+	}
+}
+
+// ----------------------------------------------------------------
+static sllv_t* mapper_reorder_before(lrec_t* pinrec, context_t* pctx, void* pvstate) {
+	mapper_reorder_state_t* pstate = (mapper_reorder_state_t*)pvstate;
+	if (pinrec != NULL) {
+		char* bvalue = lrec_get(pinrec, pstate->before_field_name);
+		if (bvalue == NULL) {
+			return sllv_single(pinrec);
+		}
+
+		lrec_t* poutrec = lrec_unbacked_alloc();
+		lrece_t* pe = pinrec->phead;
+
+		for (; pe != NULL; pe = pe->pnext) {
+			if (streq(pe->key, pstate->before_field_name)) {
+				break;
+			}
+			if (!hss_has(pstate->pfield_name_set, pe->key)) {
+				lrec_put(poutrec, mlr_strdup_or_die(pe->key), mlr_strdup_or_die(pe->value),
+					FREE_ENTRY_KEY|FREE_ENTRY_VALUE);
+			}
+		}
+
+		for (sllse_t* pf = pstate->pfield_name_list->phead; pf != NULL; pf = pf->pnext) {
+			char* field_name = pf->value;
+			char* value = lrec_get(pinrec, field_name);
+			if (value != NULL) {
+				lrec_put(poutrec, field_name, mlr_strdup_or_die(value), FREE_ENTRY_VALUE);
+			}
+		}
+
+		lrec_put(poutrec, pstate->before_field_name, mlr_strdup_or_die(bvalue), FREE_ENTRY_VALUE);
+
+		for (; pe != NULL; pe = pe->pnext) {
+			if (streq(pe->key, pstate->before_field_name)) {
+				continue;
+			}
+			if (!hss_has(pstate->pfield_name_set, pe->key)) {
+				lrec_put(poutrec, mlr_strdup_or_die(pe->key), mlr_strdup_or_die(pe->value),
+					FREE_ENTRY_KEY|FREE_ENTRY_VALUE);
+			}
+		}
+
+		lrec_free(pinrec);
+		return sllv_single(poutrec);
+	} else {
+		return sllv_single(NULL);
+	}
+}
+
+// ----------------------------------------------------------------
+static sllv_t* mapper_reorder_after(lrec_t* pinrec, context_t* pctx, void* pvstate) {
+	mapper_reorder_state_t* pstate = (mapper_reorder_state_t*)pvstate;
+	if (pinrec != NULL) {
+		char* avalue = lrec_get(pinrec, pstate->after_field_name);
+		if (avalue == NULL) {
+			return sllv_single(pinrec);
+		}
+
+		lrec_t* poutrec = lrec_unbacked_alloc();
+		lrece_t* pe = pinrec->phead;
+
+		for (; pe != NULL; pe = pe->pnext) {
+			if (streq(pe->key, pstate->after_field_name)) {
+				break;
+			}
+			if (!hss_has(pstate->pfield_name_set, pe->key)) {
+				lrec_put(poutrec, mlr_strdup_or_die(pe->key), mlr_strdup_or_die(pe->value),
+					FREE_ENTRY_KEY|FREE_ENTRY_VALUE);
+			}
+		}
+
+		lrec_put(poutrec, pstate->after_field_name, mlr_strdup_or_die(avalue), FREE_ENTRY_VALUE);
+
+		for (sllse_t* pf = pstate->pfield_name_list->phead; pf != NULL; pf = pf->pnext) {
+			char* field_name = pf->value;
+			char* value = lrec_get(pinrec, field_name);
+			if (value != NULL) {
+				lrec_put(poutrec, field_name, mlr_strdup_or_die(value), FREE_ENTRY_VALUE);
+			}
+		}
+
+		for (; pe != NULL; pe = pe->pnext) {
+			if (streq(pe->key, pstate->after_field_name)) {
+				continue;
+			}
+			if (!hss_has(pstate->pfield_name_set, pe->key)) {
+				lrec_put(poutrec, mlr_strdup_or_die(pe->key), mlr_strdup_or_die(pe->value),
+					FREE_ENTRY_KEY|FREE_ENTRY_VALUE);
+			}
+		}
+
+		lrec_free(pinrec);
+		return sllv_single(poutrec);
+	} else {
+		return sllv_single(NULL);
+	}
+}

c/reg_test/expected/out

@@ -52706,6 +52706,36 @@ y/,x/,i/,b/,a/
 0.803142013402256216,0.000047786161325772/,3/,pan/,zee/
 0.573903236805416328,0.676537984365847889/,4/,hat/,zee/
 
+mlr --from ./reg_test/input/reorder.dkvp reorder -f x,y -b u
+s=1,t=2,x=6,y=7,u=3,v=4,w=5,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,v -b x
+s=1,t=2,w=5,u=3,v=4,x=6,y=7,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f z,w,s -b v
+t=2,u=3,z=8,w=5,s=1,v=4,x=6,y=7
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,v -b nonesuch
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,nonesuch -b x
+s=1,t=2,v=4,w=5,u=3,x=6,y=7,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f x,y -a u
+s=1,t=2,u=3,x=6,y=7,v=4,w=5,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,v -a x
+s=1,t=2,w=5,x=6,u=3,v=4,y=7,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f z,w,s -a v
+t=2,u=3,v=4,z=8,w=5,s=1,x=6,y=7
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,v -a nonesuch
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8
+
+mlr --from ./reg_test/input/reorder.dkvp reorder -f u,nonesuch -a x
+s=1,t=2,v=4,w=5,x=6,u=3,y=7,z=8
+
 mlr --icsv --otsv -N cat
 a	b	c
 1	2	3

c/reg_test/input/Makefile.am

@@ -155,6 +155,7 @@ EXTRA_DIST=	\
 		regex.dkvp \
 		regularize.dkvp \
 		remove-empty-columns.csv \
+		reorder.dkvp \
 		repeat-input.dat \
 		repeats.dkvp \
 		reshape-long-ragged.dkvp \

c/reg_test/input/reorder.dkvp

@@ -0,0 +1 @@
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8

c/reg_test/run

@@ -6469,6 +6469,18 @@ run_mlr --implicit-csv-header --icsv --ifs /, --opprint cut -x -f 2  $indir/mult
 run_mlr --csv -N reorder -f 1,3,2,5,4 $indir/multi-sep.csv-crlf
 run_mlr --csv -N reorder -f 5,4,3,2,1 $indir/multi-sep.csv-crlf
 
+run_mlr --from $indir/reorder.dkvp reorder -f x,y -b u
+run_mlr --from $indir/reorder.dkvp reorder -f u,v -b x
+run_mlr --from $indir/reorder.dkvp reorder -f z,w,s -b v
+run_mlr --from $indir/reorder.dkvp reorder -f u,v -b nonesuch
+run_mlr --from $indir/reorder.dkvp reorder -f u,nonesuch -b x
+
+run_mlr --from $indir/reorder.dkvp reorder -f x,y -a u
+run_mlr --from $indir/reorder.dkvp reorder -f u,v -a x
+run_mlr --from $indir/reorder.dkvp reorder -f z,w,s -a v
+run_mlr --from $indir/reorder.dkvp reorder -f u,v -a nonesuch
+run_mlr --from $indir/reorder.dkvp reorder -f u,nonesuch -a x
+
 run_mlr --icsv --otsv -N cat <<EOF
 a,b,c
 1,2,3

docs/reference-verbs.rst

@@ -2042,9 +2042,15 @@ reorder
 
     $ mlr reorder --help
     Usage: mlr reorder [options]
-    -f {a,b,c}   Field names to reorder.
-    -e           Put specified field names at record end: default is to put
-                 them at record start.
+    -f {a,b,c} Field names to reorder.
+    -e         Put specified field names at record end: default is to put
+               them at record start.
+    -b {x}     Put field names specified with -f before field name specified by {x},
+               if any. If {x} isn't present in a given record, the specified fields
+               will not be moved.
+    -a {x}     Put field names specified with -f after field name specified by {x},
+               if any. If {x} isn't present in a given record, the specified fields
+               will not be moved.
     Examples:
     mlr reorder    -f a,b sends input record "d=4,b=2,a=1,c=3" to "a=1,b=2,d=4,c=3".
     mlr reorder -e -f a,b sends input record "d=4,b=2,a=1,c=3" to "d=4,c=3,a=1,b=2".

go/regtest/cases/cli-help/0001/expout

@@ -514,6 +514,12 @@ Moves specified names to start of record, or end of record.
 Options:
 -e Put specified field names at record end: default is to put them at record start.
 -f {a,b,c} Field names to reorder.
+-b {x}     Put field names specified with -f before field name specified by {x},
+           if any. If {x} isn't present in a given record, the specified fields
+           will not be moved.
+-a {x}     Put field names specified with -f after field name specified by {x},
+           if any. If {x} isn't present in a given record, the specified fields
+           will not be moved.
 -h|--help Show this message.
 
 Examples:

go/regtest/cases/verb-reorder/after-0001/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f x,y -a u

go/regtest/cases/verb-reorder/after-0001/expout

@@ -0,0 +1 @@
+s=1,t=2,u=3,x=6,y=7,v=4,w=5,z=8

go/regtest/cases/verb-reorder/after-0002/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,v -a x

go/regtest/cases/verb-reorder/after-0002/expout

@@ -0,0 +1 @@
+s=1,t=2,w=5,x=6,u=3,v=4,y=7,z=8

go/regtest/cases/verb-reorder/after-0003/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f z,w,s -a v

go/regtest/cases/verb-reorder/after-0003/expout

@@ -0,0 +1 @@
+t=2,u=3,v=4,z=8,w=5,s=1,x=6,y=7

go/regtest/cases/verb-reorder/after-0004/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,v -a nonesuch

go/regtest/cases/verb-reorder/after-0004/expout

@@ -0,0 +1 @@
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8

go/regtest/cases/verb-reorder/after-0005/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,nonesuch -a x

go/regtest/cases/verb-reorder/after-0005/expout

@@ -0,0 +1 @@
+s=1,t=2,v=4,w=5,x=6,u=3,y=7,z=8

go/regtest/cases/verb-reorder/before-0001/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f x,y -b u

go/regtest/cases/verb-reorder/before-0001/expout

@@ -0,0 +1 @@
+s=1,t=2,x=6,y=7,u=3,v=4,w=5,z=8

go/regtest/cases/verb-reorder/before-0002/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,v -b x

go/regtest/cases/verb-reorder/before-0002/expout

@@ -0,0 +1 @@
+s=1,t=2,w=5,u=3,v=4,x=6,y=7,z=8

go/regtest/cases/verb-reorder/before-0003/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f z,w,s -b v

go/regtest/cases/verb-reorder/before-0003/expout

@@ -0,0 +1 @@
+t=2,u=3,z=8,w=5,s=1,v=4,x=6,y=7

go/regtest/cases/verb-reorder/before-0004/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,v -b nonesuch

go/regtest/cases/verb-reorder/before-0004/expout

@@ -0,0 +1 @@
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8

go/regtest/cases/verb-reorder/before-0005/cmd

@@ -0,0 +1 @@
+mlr --from regtest/input/reorder.dkvp reorder -f u,nonesuch -b x

go/regtest/cases/verb-reorder/before-0005/expout

@@ -0,0 +1 @@
+s=1,t=2,v=4,w=5,u=3,x=6,y=7,z=8

go/regtest/input/reorder.dkvp

@@ -0,0 +1 @@
+s=1,t=2,u=3,v=4,w=5,x=6,y=7,z=8

go/src/transformers/reorder.go

@@ -26,26 +26,26 @@ func transformerReorderUsage(
 	doExit bool,
 	exitCode int,
 ) {
-	fmt.Fprintf(o, "Usage: %s %s [options]\n", lib.MlrExeName(), verbNameReorder)
+	argv0 := lib.MlrExeName()
+	verb := verbNameReorder
+	fmt.Fprintf(o, "Usage: %s %s [options]\n", argv0, verb)
 	fmt.Fprint(o,
 		`Moves specified names to start of record, or end of record.
 `)
 	fmt.Fprintf(o, "Options:\n")
 	fmt.Fprintf(o, "-e Put specified field names at record end: default is to put them at record start.\n")
 	fmt.Fprintf(o, "-f {a,b,c} Field names to reorder.\n")
+	fmt.Fprintf(o, "-b {x}     Put field names specified with -f before field name specified by {x},\n")
+	fmt.Fprintf(o, "           if any. If {x} isn't present in a given record, the specified fields\n")
+	fmt.Fprintf(o, "           will not be moved.\n")
+	fmt.Fprintf(o, "-a {x}     Put field names specified with -f after field name specified by {x},\n")
+	fmt.Fprintf(o, "           if any. If {x} isn't present in a given record, the specified fields\n")
+	fmt.Fprintf(o, "           will not be moved.\n")
 	fmt.Fprintf(o, "-h|--help Show this message.\n")
 	fmt.Fprintf(o, "\n")
 	fmt.Fprintf(o, "Examples:\n")
-	fmt.Fprintf(
-		o,
-		"%s %s    -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"a=1,b=2,d=4,c=3\".\n",
-		lib.MlrExeName(), verbNameReorder,
-	)
-	fmt.Fprintf(
-		o,
-		"%s %s -e -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"d=4,c=3,a=1,b=2\".\n",
-		lib.MlrExeName(), verbNameReorder,
-	)
+	fmt.Fprintf(o, "%s %s    -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"a=1,b=2,d=4,c=3\".\n", argv0, verb)
+	fmt.Fprintf(o, "%s %s -e -f a,b sends input record \"d=4,b=2,a=1,c=3\" to \"d=4,c=3,a=1,b=2\".\n", argv0, verb)
 
 	if doExit {
 		os.Exit(exitCode)
@@ -67,6 +67,8 @@ func transformerReorderParseCLI(
 
 	var fieldNames []string = nil
 	putAtEnd := false
+	beforeFieldName := ""
+	afterFieldName := ""
 
 	for argi < argc /* variable increment: 1 or 2 depending on flag */ {
 		opt := args[argi]
@@ -81,8 +83,20 @@ func transformerReorderParseCLI(
 		} else if opt == "-f" {
 			fieldNames = cliutil.VerbGetStringArrayArgOrDie(verb, opt, args, &argi, argc)
 
+		} else if opt == "-b" {
+			beforeFieldName = cliutil.VerbGetStringArgOrDie(verb, opt, args, &argi, argc)
+			afterFieldName = ""
+			putAtEnd = false
+
+		} else if opt == "-a" {
+			afterFieldName = cliutil.VerbGetStringArgOrDie(verb, opt, args, &argi, argc)
+			beforeFieldName = ""
+			putAtEnd = false
+
 		} else if opt == "-e" {
 			putAtEnd = true
+			beforeFieldName = ""
+			afterFieldName = ""
 
 		} else {
 			transformerReorderUsage(os.Stderr, true, 1)
@@ -96,6 +110,8 @@ func transformerReorderParseCLI(
 	transformer, _ := NewTransformerReorder(
 		fieldNames,
 		putAtEnd,
+		beforeFieldName,
+		afterFieldName,
 	)
 
 	*pargi = argi
@@ -105,7 +121,10 @@ func transformerReorderParseCLI(
 // ----------------------------------------------------------------
 type TransformerReorder struct {
 	// input
-	fieldNames []string
+	fieldNames      []string
+	fieldNamesSet   map[string]bool
+	beforeFieldName string
+	afterFieldName  string
 
 	// state
 	recordTransformerFunc transforming.RecordTransformerFunc
@@ -114,20 +133,26 @@ type TransformerReorder struct {
 func NewTransformerReorder(
 	fieldNames []string,
 	putAtEnd bool,
+	beforeFieldName string,
+	afterFieldName string,
 ) (*TransformerReorder, error) {
 
-	if !putAtEnd {
-		lib.ReverseStringList(fieldNames)
-	}
-
 	this := &TransformerReorder{
-		fieldNames: fieldNames,
+		fieldNames:      fieldNames,
+		fieldNamesSet:   lib.StringListToSet(fieldNames),
+		beforeFieldName: beforeFieldName,
+		afterFieldName:  afterFieldName,
 	}
 
-	if !putAtEnd {
-		this.recordTransformerFunc = this.reorderToStart
-	} else {
+	if putAtEnd {
 		this.recordTransformerFunc = this.reorderToEnd
+	} else if beforeFieldName != "" {
+		this.recordTransformerFunc = this.reorderBefore
+	} else if afterFieldName != "" {
+		this.recordTransformerFunc = this.reorderAfter
+	} else {
+		this.recordTransformerFunc = this.reorderToStart
+		lib.ReverseStringList(this.fieldNames)
 	}
 
 	return this, nil
@@ -173,3 +198,113 @@ func (this *TransformerReorder) reorderToEnd(
 		outputChannel <- inrecAndContext // end-of-stream marker
 	}
 }
+
+// ----------------------------------------------------------------
+func (this *TransformerReorder) reorderBefore(
+	inrecAndContext *types.RecordAndContext,
+	outputChannel chan<- *types.RecordAndContext,
+) {
+	if !inrecAndContext.EndOfStream {
+		inrec := inrecAndContext.Record
+		if inrec.Get(this.beforeFieldName) == nil {
+			outputChannel <- inrecAndContext
+			return
+		}
+
+		outrec := types.NewMlrmapAsRecord()
+		pe := inrec.Head
+
+		// * inrec will be GC'ed
+		// * We will use outrec.PutReference not output.PutCopy since inrec will be GC'ed
+
+		for ; pe != nil; pe = pe.Next {
+			if pe.Key == this.beforeFieldName {
+				break
+			}
+			if !this.fieldNamesSet[pe.Key] {
+				outrec.PutReference(pe.Key, pe.Value)
+			}
+		}
+
+		for _, fieldName := range this.fieldNames {
+			value := inrec.Get(fieldName)
+			if value != nil {
+				outrec.PutReference(fieldName, value)
+			}
+		}
+
+		value := inrec.Get(this.beforeFieldName)
+		if value != nil {
+			outrec.PutReference(this.beforeFieldName, value)
+		}
+
+		for ; pe != nil; pe = pe.Next {
+			if pe.Key != this.beforeFieldName && !this.fieldNamesSet[pe.Key] {
+				outrec.PutReference(pe.Key, pe.Value)
+			}
+		}
+
+		for _, fieldName := range this.fieldNames {
+			inrec.MoveToHead(fieldName)
+		}
+		outputChannel <- types.NewRecordAndContext(outrec, &inrecAndContext.Context)
+
+	} else {
+		outputChannel <- inrecAndContext // end-of-stream marker
+	}
+}
+
+// ----------------------------------------------------------------
+func (this *TransformerReorder) reorderAfter(
+	inrecAndContext *types.RecordAndContext,
+	outputChannel chan<- *types.RecordAndContext,
+) {
+	if !inrecAndContext.EndOfStream {
+		inrec := inrecAndContext.Record
+		if inrec.Get(this.afterFieldName) == nil {
+			outputChannel <- inrecAndContext
+			return
+		}
+
+		outrec := types.NewMlrmapAsRecord()
+		pe := inrec.Head
+
+		// * inrec will be GC'ed
+		// * We will use outrec.PutReference not output.PutCopy since inrec will be GC'ed
+
+		for ; pe != nil; pe = pe.Next {
+			if pe.Key == this.afterFieldName {
+				break
+			}
+			if !this.fieldNamesSet[pe.Key] {
+				outrec.PutReference(pe.Key, pe.Value)
+			}
+		}
+
+		value := inrec.Get(this.afterFieldName)
+		if value != nil {
+			outrec.PutReference(this.afterFieldName, value)
+		}
+
+		for _, fieldName := range this.fieldNames {
+			value := inrec.Get(fieldName)
+			if value != nil {
+				outrec.PutReference(fieldName, value)
+			}
+		}
+
+		for ; pe != nil; pe = pe.Next {
+			if pe.Key != this.afterFieldName && !this.fieldNamesSet[pe.Key] {
+				outrec.PutReference(pe.Key, pe.Value)
+			}
+		}
+
+		for _, fieldName := range this.fieldNames {
+			inrec.MoveToHead(fieldName)
+		}
+		outputChannel <- types.NewRecordAndContext(outrec, &inrecAndContext.Context)
+
+	} else {
+		outputChannel <- inrecAndContext // end-of-stream marker
+	}
+}

go/u/gg

@@ -3,7 +3,7 @@
 path_to_mlr="./mlr"
 indir="./regtest/input"
 
-go build mlr.go
+#go build mlr.go
 if [ $? -ne 0 ]; then
   exit 1
 fi
@@ -53,37 +53,16 @@ mention() {
 
 # ================================================================
 
-echo 'x=a;b;c'                         | run_mlr nest -evF -f x
-echo 'foo=bar,x=a;b;c'                 | run_mlr nest -evF -f x
-echo 'x=a;b;c,foo=bar'                 | run_mlr nest -evF -f x
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f x,y -b u
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,v -b x
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f z,w,s -b v
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,v -b nonesuch
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,nonesuch -b x
 
-echo 'x=a;b;c'                         | run_mlr nest -evR -f x
-echo 'foo=bar,x=a;b;c'                 | run_mlr nest -evR -f x
-echo 'x=a;b;c,foo=bar'                 | run_mlr nest -evR -f x
-
-echo 'x=a|b|c'                         | run_mlr nest -evF -S pipe -f x
-echo 'foo=bar,x=a|b|c'                 | run_mlr nest -evF -S pipe -f x
-echo 'x=a|b|c,foo=bar'                 | run_mlr nest -evF -S pipe -f x
-
-echo 'x=a|b|c'                         | run_mlr nest -evF -S '|' -f x
-echo 'foo=bar,x=a|b|c'                 | run_mlr nest -evF -S '|' -f x
-echo 'x=a|b|c,foo=bar'                 | run_mlr nest -evF -S '|' -f x
-
-echo 'x=a;b;c'                         | run_mlr nest -evR -f x
-echo 'foo=bar,x=a;b;c'                 | run_mlr nest -evR -f x
-echo 'x=a;b;c,foo=bar'                 | run_mlr nest -evR -f x
-
-
-echo 'x=a:1;b:2;c:3'                   | run_mlr nest -epF -f x
-echo 'foo=bar,x=a:1;b:2;c:3'           | run_mlr nest -epF -f x
-echo 'x=a:1;b:2;c:3,foo=bar'           | run_mlr nest -epF -f x
-
-echo 'x=a:1;b:2;c:3'                   | run_mlr nest -epR -f x
-echo 'foo=bar,x=a:1;b:2;c:3'           | run_mlr nest -epR -f x
-echo 'x=a:1;b:2;c:3,foo=bar'           | run_mlr nest -epR -f x
-
-echo 'x_1=a:1,x_2=b:2,x_3=c:3'         | run_mlr nest -ivF -f x
-echo 'foo=bar,x_1=a:1,x_2=b:2,x_3=c:3' | run_mlr nest -ivF -f x
-echo 'x_1=a:1,x_2=b:2,x_3=c:3,foo=bar' | run_mlr nest -ivF -f x
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f x,y -a u
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,v -a x
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f z,w,s -a v
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,v -a nonesuch
+run_mlr --from ../go/regtest/input/reorder.dkvp reorder -f u,nonesuch -a x
 
 # ================================================================