Begin work on text editing

Along with lots of stuff I was too lazy to commit separately

include/buffer.h

@@ -20,6 +20,7 @@ void buffer_read_file(struct buffer *buffer, const char *filename);
 void buffer_append_row(struct buffer *buffer, const char *chars, int n_chars);
 
 void erow_update_rendering(struct erow *erow);
+void erow_insert_char(struct erow *erow, int at, char c);
 int erow_cx_to_rx(struct erow *erow, int cx);
 int erow_rx_to_cx(struct erow *erow, int rx);
 

include/commands.h

@@ -3,6 +3,7 @@
 
 #include "input.h"
 
-void editor_move_cursor(KEY key);
+void command_move_cursor(KEY key);
+void command_insert_char(char c);
 
 #endif // COMMANDS_H

include/kilo.h

@@ -20,4 +20,6 @@ struct editor_state {
 };
 extern struct editor_state E;
 
+void editor_set_message(const char *, ...);
+
 #endif // KILO_H

src/buffer.c

@@ -64,6 +64,9 @@ void buffer_append_row(struct buffer *buffer, const char *chars, int n_chars) {
     memcpy(new_row->chars, chars, n_chars);
     new_row->n_chars = n_chars;
 
+    new_row->rchars = NULL;
+    new_row->n_rchars = 0;
+
     erow_update_rendering(new_row);
 }
 
@@ -116,6 +119,19 @@ void erow_update_rendering(struct erow *erow) {
     free(line_buffer);
 }
 
+void erow_insert_char(struct erow *erow, int at, char c) {
+    if (at < 0) at = 0;
+    if (at > erow->n_chars) at = erow->n_chars;
+
+    erow->chars = realloc(erow->chars, erow->n_chars + 1);
+    memmove(erow->chars + at + 1, erow->chars + at, erow->n_chars - at);
+
+    erow->chars[at] = c;
+    erow->n_chars++;
+
+    erow_update_rendering(erow);
+}
+
 int erow_cx_to_rx(struct erow *erow, int cx) {
     int rx = 0;
 

src/commands.c

@@ -1,33 +1,33 @@
 #include <stdbool.h>
 
 #include "commands.h"
+#include "input.h"
 #include "kilo.h"
 #include "buffer.h"
 
-void editor_move_cursor(KEY key) {
+static void cursor_adjust_viewport(void);
+static void cursor_check_file_bounds(bool horizontal);
+static void cursor_update_rx(bool horizontal);
+
+void command_move_cursor(KEY key) {
     struct erow *rows = E.current_buf->rows;
     int n_rows = E.current_buf->n_rows;
 
-    struct erow *current_row = (E.cy < n_rows ? rows + E.cy : NULL);
+    struct erow *current_row = (rows && E.cy < n_rows ? rows + E.cy : NULL);
     int max_x = (current_row ? current_row->n_chars : 0);
 
     switch (key) {
         case ARROW_LEFT:
-            if (E.cx > 0) E.cx--;
-            else if (E.cy > 0) E.cx = rows[--E.cy].n_chars;
+            E.cx--;
             break;
         case ARROW_DOWN:
-            if (E.cy < n_rows) E.cy++;
+            E.cy++;
             break;
         case ARROW_UP:
-            if (E.cy > 0) E.cy--;
+            E.cy--;
             break;
         case ARROW_RIGHT:
-            if (E.cx < max_x) E.cx++;
-            else if (E.cy < n_rows) {
-                E.cx = 0;
-                E.cy++;
-            }
+            E.cx++;
             break;
 
         case HOME:
@@ -38,29 +38,76 @@ void editor_move_cursor(KEY key) {
             break;
 
         case PG_UP:
-            if ((E.cy -= E.screenrows) < 0)
-                E.cy = 0;
+            E.cy -= E.screenrows;
             break;
         case PG_DOWN:
-            if ((E.cy += E.screenrows) > n_rows)
-                E.cy = n_rows;
+            E.cy += E.screenrows;
             break;
     }
 
-    current_row = (E.cy < n_rows ? rows + E.cy : NULL);
-    max_x = (current_row ? current_row->n_chars : 0);
+    bool horizontal = (key == ARROW_LEFT  || 
+                       key == ARROW_RIGHT ||
+                       key == HOME        ||
+                       key == END);
+
+    cursor_check_file_bounds(horizontal);
+    cursor_update_rx(horizontal);
+    cursor_adjust_viewport();
+}
+
+void command_insert_char(char c) {
+    if (E.cy == E.current_buf->n_rows)
+        buffer_append_row(E.current_buf, NULL, 0);
+
+    erow_insert_char(E.current_buf->rows+E.cy, E.cx++, c);
+    E.rx = erow_cx_to_rx(E.current_buf->rows+E.cy, E.cx);
+}
+
+static void cursor_check_file_bounds(bool horizontal) {
+    struct erow *rows = E.current_buf->rows;
+    int n_rows = E.current_buf->n_rows;
+
+    struct erow *current_row = (rows && E.cy < n_rows ? rows + E.cy : NULL);
+    int max_x = (current_row ? current_row->n_chars : 0);
+
+    if (E.cy < 0)
+        E.cy = 0;
+
+    if (E.cy > n_rows)
+        E.cy = n_rows;
+
+    if (E.cx < 0) {
+        if (E.cy > 0 && horizontal) E.cx = rows[--E.cy].n_chars;
+        else E.cx = 0;
+    }
+
+    if (E.cx > max_x) {
+        if (E.cy < n_rows && horizontal) {
+            E.cx = 0;
+            E.cy++;
+        } else E.cx = max_x;
+    }
+}
+
+static void cursor_update_rx(bool horizontal) {
+    struct erow *rows = E.current_buf->rows;
+    int n_rows = E.current_buf->n_rows;
+
+    struct erow *current_row = (rows && E.cy < n_rows ? rows + E.cy : NULL);
+    int max_x = (current_row ? current_row->n_chars : 0);
 
     static int saved_rx = 0;
-    bool horizontal = (key == ARROW_LEFT || key == ARROW_RIGHT ||
-        key == HOME || key == END);
     if (horizontal) saved_rx = erow_cx_to_rx(current_row, E.cx);
-    else E.cx = erow_rx_to_cx(current_row, saved_rx);
+    else {
+        E.cx = erow_rx_to_cx(current_row, saved_rx);
+        if (E.cx > max_x)
+            E.cx = max_x;
+    }
 
-    if (E.cx > max_x)
-        E.cx = max_x;
-
-    E.rx = erow_cx_to_rx(&E.current_buf->rows[E.cy], E.cx);
+    E.rx = erow_cx_to_rx(rows + E.cy, E.cx);
+}
 
+static void cursor_adjust_viewport(void) {
     int max_row_off = E.cy;
     if (E.row_off > max_row_off)
         E.row_off = max_row_off;

src/input.c

@@ -3,6 +3,7 @@
 #include "input.h"
 #include "terminal.h"
 #include "commands.h"
+#include "utils.h"
 
 void input_process_key(void) {
     KEY c = terminal_read_key();
@@ -16,12 +17,23 @@ void input_process_key(void) {
         case END:
         case PG_UP:
         case PG_DOWN:
-            editor_move_cursor(c);
+            command_move_cursor(c);
             break;
 
         case CTRL_KEY('Q'):
             terminal_clear();
             exit(0);
             break;
+
+        case '\r':
+            break;
+
+        case 127:
+        case DEL:
+        case CTRL_KEY('H'):
+            break;
+
+        default:
+            command_insert_char(c);
     }
 }

src/kilo.c

@@ -1,3 +1,4 @@
+#include <ctype.h>
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -11,7 +12,6 @@
 #include "terminal.h"
 
 void editor_init(char *filename);
-void editor_set_message(const char *, ...);
 
 struct editor_state E;
 
@@ -46,6 +46,7 @@ void editor_init(char *filename) {
         buffer_read_file(E.current_buf, filename);
 
     editor_set_message("Welcome to kilo. Press CTRL-Q to quit.");
+    terminal_clear();
 }
 
 void editor_set_message(const char *fmt, ...) {

src/terminal.c

@@ -89,6 +89,7 @@ ERRCODE terminal_set_cursor_pos(int row, int col) {
 
 KEY terminal_read_key(void) {
     char c;
+    int n;
     while (read(STDIN_FILENO, &c, 1) == 0);
 
     if (c == '\x1b') {
@@ -98,7 +99,11 @@ KEY terminal_read_key(void) {
             if (read(STDIN_FILENO, buf+i, 1) == 0) break;
 
             char escape_char;
-            if (sscanf(buf, "[%c~", &escape_char) != EOF) {
+            int escape_int;
+
+            n = 0;
+            sscanf(buf, "[%c%n", &escape_char, &n);
+            if (n > 0) {
                 switch (escape_char) {
                     case 'A': return ARROW_UP;
                     case 'B': return ARROW_DOWN;
@@ -109,15 +114,18 @@ KEY terminal_read_key(void) {
                 }
             }
 
-            if (sscanf(buf, "O%c", &escape_char) != EOF) {
+            n = 0;
+            sscanf(buf, "O%c%n", &escape_char, &n);
+            if (n > 0) {
                 switch (escape_char) {
                     case 'H': return HOME;
                     case 'F': return END;
                 }
             }
 
-            int escape_int;
-            if (sscanf(buf, "[%d~", &escape_int) != EOF) {
+            n = 0;
+            sscanf(buf, "[%d~%n", &escape_int, &n);
+            if (n > 0) {
                 switch (escape_int) {
                     case 1:
                     case 7: