acme: preserve window position and selection during Get

Before, executing Get in a file rewound the window offset and
selection to the start of the file.

After this CL, Get preserves the window offset and selection,
where preserve is defined as "the same line number and rune
offset within the line". So if the window started at line 10
before and the selection was line 13 chars 5-7, then that
will still be true after Get, provided the new content is large
enough.

This should help the common situation of plumbing a
compiler error, realizing the window is out of date,
clicking Get, and then losing the positioning from the
plumb operation.

5 files changed, 103 insertions, 18 deletions

diff --git a/src/cmd/acme/addr.c b/src/cmd/acme/addr.c
index 861e5e01..2ccae960 100644
--- a/src/cmd/acme/addr.c
+++ b/src/cmd/acme/addr.c
@@ -49,6 +49,27 @@ isregexc(int r)
 	return FALSE;
 }
 
+// nlcounttopos starts at q0 and advances nl lines,
+// being careful not to walk past the end of the text,
+// and then nr chars, being careful not to walk past
+// the end of the current line.
+// It returns the final position.
+long
+nlcounttopos(Text *t, long q0, long nl, long nr)
+{
+	while(nl > 0 && q0 < t->file->b.nc) {
+		if(textreadc(t, q0++) == '\n')
+			nl--;
+	}
+	if(nl > 0)
+		return q0;
+	while(nr > 0 && q0 < t->file->b.nc && textreadc(t, q0) != '\n') {
+		q0++;
+		nr--;
+	}
+	return q0;
+}
+
 Range
 number(uint showerr, Text *t, Range r, int line, int dir, int size, int *evalp)
 {
diff --git a/src/cmd/acme/ecmd.c b/src/cmd/acme/ecmd.c
index 9bedae4c..ef92e339 100644
--- a/src/cmd/acme/ecmd.c
+++ b/src/cmd/acme/ecmd.c
@@ -661,15 +661,16 @@ pipe_cmd(Text *t, Cmd *cp)
 }
 
 long
-nlcount(Text *t, long q0, long q1)
+nlcount(Text *t, long q0, long q1, long *pnr)
 {
-	long nl;
+	long nl, start;
 	Rune *buf;
 	int i, nbuf;
 
 	buf = fbufalloc();
 	nbuf = 0;
 	i = nl = 0;
+	start = q0;
 	while(q0 < q1){
 		if(i == nbuf){
 			nbuf = q1-q0;
@@ -678,24 +679,44 @@ nlcount(Text *t, long q0, long q1)
 			bufread(&t->file->b, q0, buf, nbuf);
 			i = 0;
 		}
-		if(buf[i++] == '\n')
+		if(buf[i++] == '\n') {
+			start = q0+1;
 			nl++;
+		}
 		q0++;
 	}
 	fbuffree(buf);
+	if(pnr != nil)
+		*pnr = q0 - start;
 	return nl;
 }
 
+enum {
+	PosnLine = 0,
+	PosnChars = 1,
+	PosnLineChars = 2,
+};
+
 void
-printposn(Text *t, int charsonly)
+printposn(Text *t, int mode)
 {
-	long l1, l2;
+	long l1, l2, r1, r2;
 
 	if (t != nil && t->file != nil && t->file->name != nil)
 		warning(nil, "%.*S:", t->file->nname, t->file->name);
-	if(!charsonly){
-		l1 = 1+nlcount(t, 0, addr.r.q0);
-		l2 = l1+nlcount(t, addr.r.q0, addr.r.q1);
+	
+	switch(mode) {
+	case PosnChars:
+		warning(nil, "#%d", addr.r.q0);
+		if(addr.r.q1 != addr.r.q0)
+			warning(nil, ",#%d", addr.r.q1);
+		warning(nil, "\n");
+		return;
+	
+	default:
+	case PosnLine:
+		l1 = 1+nlcount(t, 0, addr.r.q0, nil);
+		l2 = l1+nlcount(t, addr.r.q0, addr.r.q1, nil);
 		/* check if addr ends with '\n' */
 		if(addr.r.q1>0 && addr.r.q1>addr.r.q0 && textreadc(t, addr.r.q1-1)=='\n')
 			--l2;
@@ -704,32 +725,43 @@ printposn(Text *t, int charsonly)
 			warning(nil, ",%lud", l2);
 		warning(nil, "\n");
 		return;
+
+	case PosnLineChars:
+		l1 = 1+nlcount(t, 0, addr.r.q0, &r1);
+		l2 = l1+nlcount(t, addr.r.q0, addr.r.q1, &r2);
+		if(l2 == l1)
+			r2 += r1;
+		warning(nil, "%lud+#%d", l1, r1);
+		if(l2 != l1)
+			warning(nil, ",%lud+#%d", l2, r2);
+		warning(nil, "\n");
+		return;
 	}
-	warning(nil, "#%d", addr.r.q0);
-	if(addr.r.q1 != addr.r.q0)
-		warning(nil, ",#%d", addr.r.q1);
-	warning(nil, "\n");
 }
 
 int
 eq_cmd(Text *t, Cmd *cp)
 {
-	int charsonly;
+	int mode;
 
 	switch(cp->u.text->n){
 	case 0:
-		charsonly = FALSE;
+		mode = PosnLine;
 		break;
 	case 1:
 		if(cp->u.text->r[0] == '#'){
-			charsonly = TRUE;
+			mode = PosnChars;
+			break;
+		}
+		if(cp->u.text->r[0] == '+'){
+			mode = PosnLineChars;
 			break;
 		}
 	default:
-		SET(charsonly);
+		SET(mode);
 		editerror("newline expected");
 	}
-	printposn(t, charsonly);
+	printposn(t, mode);
 	return TRUE;
 }
 
diff --git a/src/cmd/acme/exec.c b/src/cmd/acme/exec.c
index 1df01c71..deaef0cb 100644
--- a/src/cmd/acme/exec.c
+++ b/src/cmd/acme/exec.c
@@ -573,15 +573,27 @@ zeroxx(Text *et, Text *t, Text *_1, int _2, int _3, Rune *_4, int _5)
 		winunlock(t->w);
 }
 
+typedef struct TextAddr TextAddr;
+struct TextAddr {
+	long lorigin; // line+rune for origin
+	long rorigin;
+	long lq0; // line+rune for q0
+	long rq0;
+	long lq1; // line+rune for q1
+	long rq1;
+};
+
 void
 get(Text *et, Text *t, Text *argt, int flag1, int _0, Rune *arg, int narg)
 {
 	char *name;
 	Rune *r;
 	int i, n, dirty, samename, isdir;
+	TextAddr *addr, *a;
 	Window *w;
 	Text *u;
 	Dir *d;
+	long q0, q1;
 
 	USED(_0);
 
@@ -606,6 +618,14 @@ get(Text *et, Text *t, Text *argt, int flag1, int _0, Rune *arg, int narg)
 			return;
 		}
 	}
+	addr = emalloc((t->file->ntext)*sizeof(TextAddr));
+	for(i=0; i<t->file->ntext; i++) {
+		a = &addr[i];
+		u = t->file->text[i];
+		a->lorigin = nlcount(u, 0, u->org, &a->rorigin);
+		a->lq0 = nlcount(u, 0, u->q0, &a->rq0);
+		a->lq1 = nlcount(u, u->q0, u->q1, &a->rq1);
+	}
 	r = bytetorune(name, &n);
 	for(i=0; i<t->file->ntext; i++){
 		u = t->file->text[i];
@@ -631,8 +651,18 @@ get(Text *et, Text *t, Text *argt, int flag1, int _0, Rune *arg, int narg)
 	for(i=0; i<t->file->ntext; i++){
 		u = t->file->text[i];
 		textsetselect(&u->w->tag, u->w->tag.file->b.nc, u->w->tag.file->b.nc);
+		if(samename) {
+			a = &addr[i];
+			// warning(nil, "%d %d %d %d %d %d\n", a->lorigin, a->rorigin, a->lq0, a->rq0, a->lq1, a->rq1);
+			q0 = nlcounttopos(u, 0, a->lq0, a->rq0);
+			q1 = nlcounttopos(u, q0, a->lq1, a->rq1);
+			textsetselect(u, q0, q1);
+			q0 = nlcounttopos(u, 0, a->lorigin, a->rorigin);
+			textsetorigin(u, q0, FALSE);
+		}
 		textscrdraw(u);
 	}
+	free(addr);
 	xfidlog(w, "get");
 }
 
diff --git a/src/cmd/acme/fns.h b/src/cmd/acme/fns.h
index 1cd35257..8dc02378 100644
--- a/src/cmd/acme/fns.h
+++ b/src/cmd/acme/fns.h
@@ -93,6 +93,8 @@ Rune*	findbl(Rune*, int, int*);
 char*	edittext(Window*, int, Rune*, int);
 void		flushwarnings(void);
 void		startplumbing(void);
+long	nlcount(Text*, long, long, long*);
+long	nlcounttopos(Text*, long, long, long);
 
 Runestr	runestr(Rune*, uint);
 Range range(int, int);
diff --git a/src/cmd/acme/text.c b/src/cmd/acme/text.c
index 4832de8e..8ff5884d 100644
--- a/src/cmd/acme/text.c
+++ b/src/cmd/acme/text.c
@@ -1615,7 +1615,7 @@ textsetorigin(Text *t, uint org, int exact)
 	Rune *r;
 	uint n;
 
-	if(org>0 && !exact){
+	if(org>0 && !exact && textreadc(t, org-1) != '\n'){
 		/* org is an estimate of the char posn; find a newline */
 		/* don't try harder than 256 chars */
 		for(i=0; i<256 && org<t->file->b.nc; i++){