Supporting using ask in the middle of a line without erasing the line.

ask.c

@@ -68,15 +68,15 @@ static int matches(const char *str, const char *patt)
     return 1;
 }
 
-static void draw_line(FILE *out, const char *line, const char *patt, int cursor)
+static void draw_line(FILE *out, const char *line, const char *patt, int cursor, int stop_at_cursor)
 {
     size_t linelen = strlen(line), patlen = strlen(patt);
     int dim = 0;
     int p = 0;
     int run = 0;
     int *cache = calloc((linelen+1)*(patlen+1), sizeof(int));
-    if (cursor >= (int)patlen)
+    if (patlen == 0 && stop_at_cursor)
-        fputs("\0337", out);
+        return;
     for (int i = 0; i < (int)linelen; i++) {
         if (EQ(patt[p], line[i]) &&
             run + lcs(line,patt,(int)linelen,(int)patlen,i,p,cache)
@@ -85,11 +85,13 @@ static void draw_line(FILE *out, const char *line, const char *patt, int cursor)
                 fputs("\033[22m", out);
                 dim = 0;
             }
+            if (cursor == p && stop_at_cursor)
+                return;
             fputc(patt[p], out);
             ++run;
             ++p;
-            if (cursor == p)
+            if (cursor == p && stop_at_cursor)
-                fputs("\0337", out);
+                return;
         } else {
             run = 0;
             if (!dim) {
@@ -99,7 +101,6 @@ static void draw_line(FILE *out, const char *line, const char *patt, int cursor)
             fputc(line[i], out);
         }
     }
-    fputs("\0338", out);
 }
 
 /*
@@ -107,39 +108,35 @@ static void draw_line(FILE *out, const char *line, const char *patt, int cursor)
  */
 static char *get_input(FILE *in, FILE *out, const char *prompt, const char *initial, int nopts, char **opts)
 {
+    fputs("\0337", out);
+    if (!prompt) prompt = "> ";
     size_t cap = initial ? strlen(initial) + 100 : 100;
     char *buf = memcheck(calloc(cap, 1));
     char *picked = NULL;
     int b = 0, len = 0;
     if (initial) {
-        if (!strcpy(buf, initial)) return NULL;
+        strcpy(buf, initial);
         len = (int)strlen(initial);
         b = len;
-        fputs(initial, out);
     }
 
     int start = 0;
-    // Show cursor and set to blinking line:
     while (1) {
-        fputs("\033[G\033[K\033[0m", out);
-        if (prompt) {
-            fputs("\033[1G\033[K\033[37;1m", out);
-            fputs(prompt, out);
-            fputs("\033[0m", out);
-        }
         case_sensitive = 0;
         for (const char *p = buf; *p; ++p)
             case_sensitive |= ('A' <= *p && *p <= 'Z');
 
         int ncandidates = 0;
         picked = NULL;
-        for (int i = 0; i < nopts; i++) {
+        if (buf[0]) {
-            int j = (start + i) % nopts;
+            for (int i = 0; i < nopts; i++) {
-            if (matches(opts[j], buf)) {
+                int j = (start + i) % nopts;
-                ++ncandidates;
+                if (matches(opts[j], buf)) {
-                if (!picked) {
+                    ++ncandidates;
-                    picked = opts[j];
+                    if (!picked) {
-                    start = j;
+                        picked = opts[j];
+                        start = j;
+                    }
                 }
             }
         }
@@ -147,6 +144,7 @@ static char *get_input(FILE *in, FILE *out, const char *prompt, const char *init
         if (quickpick && ncandidates == 1 && picked)
             goto finished;
 
+        fprintf(out, "\0338\033[K\033[0;1m%s\033[0m", prompt);
         if (password) {
             if (picked) fputs("\033[0;32m", out);
             else if (nopts > 0) fputs("\033[0;31m", out);
@@ -155,7 +153,13 @@ static char *get_input(FILE *in, FILE *out, const char *prompt, const char *init
             fputs("\033[0m", out);
         } else {
             if (picked) {
-                draw_line(out, picked, buf, b);
+                // Because stuff can have tabs and whatnot and the saved cusor
+                // position is already in use, the most reliable way to make
+                // sure the cursor ends up in the right place is to draw the
+                // whole line, then redraw everything up to the cursor.
+                draw_line(out, picked, buf, b, 0);
+                fprintf(out, "\0338\033[0m\033[37;1m%s\033[0m", prompt);
+                draw_line(out, picked, buf, b, 1);
             } else {
                 if (nopts > 0)
                     fprintf(out, "\033[0;31m%s\033[0m", buf);
@@ -254,6 +258,7 @@ static char *get_input(FILE *in, FILE *out, const char *prompt, const char *init
   finished:
     if (picked) picked = memcheck(strdup(picked));
     else picked = buf;
+    fputs("\0338\033[0m\033[K", out);
     return picked;
 }
 
@@ -313,7 +318,6 @@ int main(int argc, char *argv[])
         ++a;
     }
     if (!prompt && a < argc) prompt = argv[a++];
-    if (!prompt) prompt = "> ";
 
     while (a < argc) {
         if ((size_t)nlines >= linescap)
@@ -323,7 +327,6 @@ int main(int argc, char *argv[])
 
     char *output = get_input(tty_in, tty_out, prompt, initial, nlines, lines);
 
-    fputs("\033[G\033[K\033[0m", tty_out);
     fflush(tty_out);
     tcsetattr(fileno(tty_out), TCSAFLUSH, &orig_termios);
     fclose(tty_out);
@@ -333,7 +336,7 @@ int main(int argc, char *argv[])
 
     if (!output) return 1;
 
-    puts(output);
+    fputs(output, stdout);
     free(output);
 
     // This doesn't free the memory in lines, but it doesn't need to because