trim trailing whitespace

1 files changed, 79 insertions, 41 deletions

diff --git a/vterm-module.c b/vterm-module.c
index 72a1e21..efe700a 100644
--- a/vterm-module.c
+++ b/vterm-module.c
@@ -201,18 +201,12 @@ static LineInfo *get_lineinfo(Term *term, int row) {
 }
 static bool is_eol(Term *term, int end_col, int row, int col) {
   /* This cell is EOL if this and every cell to the right is black */
-  if (row >= 0) {
-    VTermPos pos = {.row = row, .col = col};
-    return vterm_screen_is_eol(term->vts, pos);
-  }
-
-  ScrollbackLine *sbrow = term->sb_buffer[-row - 1];
-  int c;
-  for (c = col; c < end_col && c < sbrow->cols;) {
-    if (sbrow->cells[c].chars[0]) {
+  VTermScreenCell cell;
+  for (int c = col; c < end_col; c++) {
+    fetch_cell(term, row, c, &cell);
+    if (!(!cell.chars[0] || (cell.width == 1 && cell.chars[0] == ' '))) {
       return 0;
     }
-    c += sbrow->cells[c].width;
   }
   return 1;
 }
@@ -232,8 +226,8 @@ static int is_end_of_prompt(Term *term, int end_col, int row, int col) {
   }
   return 0;
 }
-
-static void goto_col(Term *term, emacs_env *env, int row, int end_col) {
+static void goto_col(Term *term, emacs_env *env, int row, int end_col,
+                     bool insert_beyond_eol) {
   int col = 0;
   size_t offset = 0;
   size_t beyond_eol = 0;
@@ -248,6 +242,9 @@ static void goto_col(Term *term, emacs_env *env, int row, int end_col) {
     if (cell.chars[0]) {
       if (cell.width > 1) {
         offset += cell.width - 1;
+      } else if (is_eol(term, term->width, row, col)) {
+        beyond_eol += cell.width;
+        offset += cell.width;
       }
     } else {
       if (is_eol(term, term->width, row, col)) {
@@ -257,11 +254,15 @@ static void goto_col(Term *term, emacs_env *env, int row, int end_col) {
     }
     col += cell.width;
   }
-
-  forward_char(env, env->make_integer(env, end_col - offset));
-  emacs_value space = env->make_string(env, " ", 1);
-  for (int i = 0; i < beyond_eol; i += 1)
-    insert(env, space);
+  int n = end_col - offset;
+  if (!insert_beyond_eol)
+    n += beyond_eol;
+  forward_char(env, env->make_integer(env, n));
+  if (insert_beyond_eol) {
+    emacs_value space = env->make_string(env, " ", 1);
+    for (int i = 0; i < beyond_eol; i += 1)
+      insert(env, space);
+  }
 }
 
 static void refresh_lines(Term *term, emacs_env *env, int start_row,
@@ -273,53 +274,88 @@ static void refresh_lines(Term *term, emacs_env *env, int start_row,
 
 #define PUSH_BUFFER(c)                                                         \
   do {                                                                         \
-    if (length == capacity) {                                                  \
+    if (length + spacelength == capacity) {                                    \
       capacity += end_col * 4;                                                 \
       buffer = realloc(buffer, capacity * sizeof(char));                       \
     }                                                                          \
-    buffer[length] = (c);                                                      \
-    length++;                                                                  \
+    if (c == ' ') {                                                            \
+      buffer[length + spacelength] = ' ';                                      \
+      spacelength++;                                                           \
+    } else {                                                                   \
+      /* only increase the line length if the last character is not            \
+       * whitespace*/                                                          \
+      buffer[length + spacelength] = (c);                                      \
+      length += 1 + spacelength;                                               \
+      spacelength = 0;                                                         \
+    }                                                                          \
   } while (0)
 
   int capacity = ((end_row - start_row + 1) * end_col) * 4;
   int length = 0;
+  int spacelength = 0; //  count of trailing whitespace
   char *buffer = malloc(capacity * sizeof(char));
   VTermScreenCell cell;
   VTermScreenCell lastCell;
   fetch_cell(term, start_row, 0, &lastCell);
 
   for (i = start_row; i < end_row; i++) {
-
+    spacelength = 0;
     int newline = 0;
-    int isprompt = 0;
+    int isprompt = 0; // is end of prompt
     for (j = 0; j < end_col; j++) {
       fetch_cell(term, i, j, &cell);
-      if (isprompt && length > 0) {
-        emacs_value text = render_text(env, term, buffer, length, &lastCell);
-        insert(env, render_prompt(env, text));
-        length = 0;
+      // This cell is EOL if this and every cell to the right is black
+      bool eol = is_eol(term, end_col, i, j);
+      if (isprompt) {     // previous cell is prompt
+        if (length > 0) { // if the prompt char is not whitespace
+          emacs_value text = render_text(env, term, buffer, length, &lastCell);
+          insert(env, render_prompt(env, text));
+          memmove(buffer, buffer + length, spacelength);
+          length = 0;
+        } else if (spacelength > 0 && !eol) {
+          // if the prompt char is whitespace and the cell is not at the end of
+          // line, then render the whitespace as prompt
+          emacs_value text =
+              render_text(env, term, buffer, length + spacelength, &lastCell);
+          insert(env, render_prompt(env, text));
+          length = 0;
+          spacelength = 0;
+        } else if (eol) {
+          // trim trailing whitespace at end of line
+          // and the prompt would be rendered after break
+          spacelength = 0;
+          PUSH_BUFFER('\n');
+          newline = 1;
+          break;
+        }
       }
 
       isprompt = is_end_of_prompt(term, end_col, i, j);
-      if (isprompt && length > 0) {
-        insert(env, render_text(env, term, buffer, length, &lastCell));
+      if (isprompt && length + spacelength > 0) {
+        insert(env,
+               render_text(env, term, buffer, length + spacelength, &lastCell));
         length = 0;
+        spacelength = 0;
       }
 
       if (!compare_cells(&cell, &lastCell)) {
+        // maybe the trailing whitespace should be rendered togther?
         emacs_value text = render_text(env, term, buffer, length, &lastCell);
         insert(env, text);
+        // move the trailing whitespace to the start of buffer
+        memmove(buffer, buffer + length, spacelength);
         length = 0;
       }
-
       lastCell = cell;
+
+      if (eol) {
+        // trim trailing whitespace at end of line
+        spacelength = 0;
+        PUSH_BUFFER('\n');
+        newline = 1;
+        break;
+      }
       if (cell.chars[0] == 0) {
-        if (is_eol(term, end_col, i, j)) {
-          /* This cell is EOL if this and every cell to the right is black */
-          PUSH_BUFFER('\n');
-          newline = 1;
-          break;
-        }
         PUSH_BUFFER(' ');
       } else {
         for (int k = 0; k < VTERM_MAX_CHARS_PER_CELL && cell.chars[k]; ++k) {
@@ -335,11 +371,13 @@ static void refresh_lines(Term *term, emacs_env *env, int start_row,
         int w = cell.width - 1;
         j = j + w;
       }
-    }
-    if (isprompt && length > 0) {
-      emacs_value text = render_text(env, term, buffer, length, &lastCell);
+    } // end of range of columns
+    if (isprompt && length + spacelength > 0) {
+      emacs_value text =
+          render_text(env, term, buffer, length + spacelength, &lastCell);
       insert(env, render_prompt(env, text));
       length = 0;
+      spacelength = 0;
       isprompt = 0;
     }
 
@@ -347,6 +385,7 @@ static void refresh_lines(Term *term, emacs_env *env, int start_row,
       emacs_value text = render_text(env, term, buffer, length, &lastCell);
       insert(env, text);
       length = 0;
+      spacelength = 0;
       text = render_fake_newline(env, term);
       insert(env, text);
     }
@@ -486,7 +525,7 @@ static void adjust_topline(Term *term, emacs_env *env) {
    */
 
   goto_line(env, pos.row - term->height);
-  goto_col(term, env, pos.row, pos.col);
+  goto_col(term, env, pos.row, pos.col, true);
 
   emacs_value windows = get_buffer_window_list(env);
   emacs_value swindow = selected_window(env);
@@ -1393,7 +1432,7 @@ emacs_value Fvterm_reset_cursor_point(emacs_env *env, ptrdiff_t nargs,
   Term *term = env->get_user_ptr(env, args[0]);
   int line = row_to_linenr(term, term->cursor.row);
   goto_line(env, line);
-  goto_col(term, env, term->cursor.row, term->cursor.col);
+  goto_col(term, env, term->cursor.row, term->cursor.col, false);
   return point(env);
 }
 
@@ -1512,6 +1551,5 @@ int emacs_module_init(struct emacs_runtime *ert) {
   bind_function(env, "vterm--get-icrnl", fun);
 
   provide(env, "vterm-module");
-
   return 0;
 }