[ncplane_put] admit tab characters #1233

include/notcurses/notcurses.h

@@ -2165,8 +2165,9 @@ ncplane_putc(struct ncplane* n, const nccell* c){
 }
 
 // Replace the cell at the specified coordinates with the provided 7-bit char
-// 'c'. Advance the cursor by 1. On success, returns 1. On failure, returns -1.
-// This works whether the underlying char is signed or unsigned.
+// 'c'. Advance the cursor by 1. On success, returns the number of columns the
+// cursor was advanced. On failure, returns -1. This works whether the
+// underlying char is signed or unsigned.
 static inline int
 ncplane_putchar_yx(struct ncplane* n, int y, int x, char c){
   nccell ce = NCCELL_INITIALIZER((uint32_t)c, ncplane_styles(n), ncplane_channels(n));

src/lib/notcurses.c

@@ -19,6 +19,7 @@
 #include "banner.h"
 
 #define ESC "\x1b"
+#define TABSTOP 8
 
 void notcurses_version_components(int* major, int* minor, int* patch, int* tweak){
   *major = NOTCURSES_VERNUM_MAJOR;
@@ -1858,8 +1859,6 @@ ncplane_put(ncplane* n, int y, int x, const char* egc, int cols,
   }
   if(*egc == '\n'){
     scroll_down(n);
-  }else if(*egc == '\t'){
-    // FIXME do what, exactly?
   }
   // A wide character obliterates anything to its immediate right (and marks
   // that cell as wide). Any character placed atop one cell of a wide character
@@ -1884,13 +1883,30 @@ ncplane_put(ncplane* n, int y, int x, const char* egc, int cols,
   }
   targ->stylemask = stylemask;
   targ->channels = channels;
-  if(cell_load_direct(n, targ, egc, bytes, cols) < 0){
-    return -1;
+  // tabs get replaced with spaces, up to the next tab stop. we always try to
+  // write at least one. if there are no more tabstops on the current line, if
+  // autogrowing to the right, extend as necessary. otherwise, if scrolling,
+  // move to the next line. otherwise, simply fill any spaces we can. this has
+  // already taken place by the time we get here, if it ought have happened.
+  if(*egc == '\t'){
+    if(n->x >= n->lenx){
+      if(!n->scrolling && n->autogrow){
+        // FIXME might need autogrow to the next tab stop out
+      }
+    }
+    if(cell_load_direct(n, targ, egc, bytes, cols) < 0){
+      return -1;
+    }
+    cols = (n->x + TABSTOP) / TABSTOP * TABSTOP;
+  }else{
+    if(cell_load_direct(n, targ, egc, bytes, cols) < 0){
+      return -1;
+    }
   }
 //fprintf(stderr, "%08x %016lx %c %d %d\n", targ->gcluster, targ->channels, nccell_double_wide_p(targ) ? 'D' : 'd', bytes, cols);
-  // must set our right hand sides wide, and check for further damage
   if(*egc != '\n'){
     ++n->x;
+    // if wide, set our right hand columns wide, and check for further damage
     for(int i = 1 ; i < cols ; ++i){
       nccell* candidate = &n->fb[nfbcellidx(n, n->y, n->x)];
       int off = nccell_cols(candidate);

src/tests/tabs.cpp

@@ -1,6 +1,8 @@
 #include <cstdlib>
 #include "main.h"
 
+constexpr int TABWIDTH = 8;
+
 TEST_CASE("TaBs") { // refreshing and delicious
   auto nc_ = testing_notcurses();
   if(!nc_){
@@ -15,10 +17,31 @@ TEST_CASE("TaBs") { // refreshing and delicious
     nopts.cols = 80;
     auto n = ncplane_create(n_, &nopts);
     unsigned y, x;
-    CHECK(1 == ncplane_putchar(n, '\t'));
+    CHECK(TABWIDTH == ncplane_putchar(n, '\t'));
     ncplane_cursor_yx(n, &y, &x);
     CHECK(y == 0);
-    CHECK(x == 8);
+    CHECK(x == TABWIDTH);
+    for(unsigned i = 0 ; i < x ; ++i){
+      char* c = ncplane_at_yx(n, 0, i, nullptr, nullptr);
+      REQUIRE(c);
+      CHECK(0 == strcmp(c, " "));
+      free(c);
+    }
+  }
+
+  SUBCASE("PutXoffsetTaBs") {
+    struct ncplane_options nopts{};
+    nopts.rows = 2;
+    nopts.cols = TABWIDTH;
+    auto n = ncplane_create(n_, &nopts);
+    unsigned y, x;
+    for(int i = 0 ; i < TABWIDTH ; ++i){
+      CHECK(TABWIDTH - i == ncplane_putchar(n, '\t'));
+      ncplane_cursor_yx(n, &y, &x);
+      CHECK(y == 0);
+      CHECK(x == TABWIDTH - i);
+      CHECK(0 == ncplane_cursor_move_yx(n, 0, i + 1));
+    }
     for(unsigned i = 0 ; i < x ; ++i){
       char* c = ncplane_at_yx(n, 0, i, nullptr, nullptr);
       REQUIRE(c);
@@ -30,13 +53,13 @@ TEST_CASE("TaBs") { // refreshing and delicious
   SUBCASE("PutwcTaB") {
     struct ncplane_options nopts{};
     nopts.rows = 2;
-    nopts.cols = 80;
+    nopts.cols = TABWIDTH;
     auto n = ncplane_create(n_, &nopts);
     unsigned y, x;
-    CHECK(1 == ncplane_putwc(n, L'\t'));
+    CHECK(TABWIDTH == ncplane_putwc(n, L'\t'));
     ncplane_cursor_yx(n, &y, &x);
     CHECK(y == 0);
-    CHECK(x == 8);
+    CHECK(x == TABWIDTH);
     for(unsigned i = 0 ; i < x ; ++i){
       char* c = ncplane_at_yx(n, 0, i, nullptr, nullptr);
       REQUIRE(c);
@@ -48,14 +71,14 @@ TEST_CASE("TaBs") { // refreshing and delicious
   SUBCASE("PutCellTaB") {
     struct ncplane_options nopts{};
     nopts.rows = 2;
-    nopts.cols = 80;
+    nopts.cols = TABWIDTH;
     auto n = ncplane_create(n_, &nopts);
     nccell c = NCCELL_CHAR_INITIALIZER('\t');
     unsigned y, x;
     CHECK(1 == ncplane_putc(n, &c));
     ncplane_cursor_yx(n, &y, &x);
     CHECK(y == 0);
-    CHECK(x == 8);
+    CHECK(x == TABWIDTH);
     for(unsigned i = 0 ; i < x ; ++i){
       char* s = ncplane_at_yx(n, 0, i, nullptr, nullptr);
       REQUIRE(s);
@@ -67,7 +90,7 @@ TEST_CASE("TaBs") { // refreshing and delicious
   SUBCASE("PutMultipleTaBs") {
     struct ncplane_options nopts{};
     nopts.rows = 2;
-    nopts.cols = 80;
+    nopts.cols = TABWIDTH;
     auto n = ncplane_create(n_, &nopts);
     unsigned y, x;
     CHECK(1 == ncplane_putstr(n, "\t\t"));
@@ -85,7 +108,7 @@ TEST_CASE("TaBs") { // refreshing and delicious
   SUBCASE("PutRowOfTaBs") {
     struct ncplane_options nopts{};
     nopts.rows = 2;
-    nopts.cols = 80;
+    nopts.cols = TABWIDTH;
     auto n = ncplane_create(n_, &nopts);
     unsigned y, x;
     CHECK(1 == ncplane_putstr(n, "\t\t\t\t\t\t\t\t\t\t"));