From ef4604d9c146dbab1a653f66209103b74e6feb36 Mon Sep 17 00:00:00 2001
From: scratko <m@scratko.xyz>
Date: Thu, 20 Jun 2024 18:38:11 +0300
Subject: Shell-edit release

Autocomplete program and file names (tab).
Moving the cursor to edit commands (left and right arrows).
Deleting a character in a command (backspace).
---
 readline.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 readline.c

(limited to 'readline.c')

diff --git a/readline.c b/readline.c
new file mode 100644
index 0000000..c36b19a
--- /dev/null
+++ b/readline.c
@@ -0,0 +1,153 @@
+#include "readline.h"
+#include "shell.h"
+
+#include <stdlib.h>
+#include <string.h> /* memmove */
+#include <stdio.h>
+
+void readline_create_array(struct readline_type *readline)
+{
+    readline->arr = calloc(initial_size, 1);
+    readline->cursor_pos = 0;
+    readline->last_element_index = -1;
+    readline->considered_index = 0;
+    readline->allocation_size = initial_size;
+}
+
+static void readline_copy_array(struct readline_type *readline, char *new_arr)
+{
+    int i;
+    for(i = 0; i <= readline->last_element_index; ++i)
+        new_arr[i] = readline->arr[i];
+}
+
+static void readline_allocate_memory(struct readline_type *readline)
+{
+    char *new_arr = calloc(readline->allocation_size * 2, 1);
+    readline_copy_array(readline, new_arr);
+    free(readline->arr);
+    readline->arr = new_arr;
+    readline->allocation_size *= 2;
+}
+
+static void readline_reprint_modified_part(struct readline_type *readline,
+                                           int begin_idx)
+{
+    int i, counter;
+    for(i = begin_idx, counter = 0; i <= readline->last_element_index;
+                                                            ++i, ++counter)
+        putchar(readline->arr[i]);
+
+    /* return cursor to previous position */
+    for( ; counter != 0; --counter)
+        putchar('\b');
+    fflush(stdout);
+}
+
+void readline_add_char(struct readline_type *readline, int ch)
+{
+    char *begin_arr;
+    int size;
+
+    if(readline->last_element_index+1 == readline->allocation_size)
+        readline_allocate_memory(readline);
+    /* insert in middle position */
+    if(readline->cursor_pos - 1 != readline->last_element_index) {
+        begin_arr = readline->arr + readline->cursor_pos;
+        size = readline->last_element_index - readline->cursor_pos + 1;
+        memmove(begin_arr+1, begin_arr, size);
+        readline->arr[readline->cursor_pos] = ch;
+        ++readline->last_element_index;
+        readline_reprint_modified_part(readline, readline->cursor_pos + 1);
+    } else {
+        ++readline->last_element_index;
+        readline->arr[readline->last_element_index] = ch;
+    }
+    ++readline->cursor_pos;
+}
+
+void readline_reset_array(struct readline_type *readline)
+{
+    readline->last_element_index = -1;
+    readline->cursor_pos = 0;
+}
+
+void readline_clear(struct readline_type *readline)
+{
+    free(readline->arr);
+    readline->arr = NULL;
+}
+
+void readline_print(struct readline_type *readline)
+{
+    int i;
+    for(i = 0; i <= readline->last_element_index; ++i)
+        putchar(readline->arr[i]);
+    readline->cursor_pos = readline->last_element_index + 1;
+    fflush(stdout);
+}
+
+enum keys readline_detect_arrow_keys(int ch)
+{
+    char next_ch;
+    if(ch == esc) {
+        next_ch = getchar();
+        if(next_ch != '[')
+            return unknown_key;
+        next_ch = getchar();
+
+        switch(next_ch) {
+        case left_arrow:
+            return left_arrow;
+        case right_arrow:
+            return right_arrow;
+        case up_arrow:
+            return up_arrow;
+        case down_arrow:
+            return down_arrow;
+        default:
+            return unknown_key;
+        }
+    }
+    return none;
+}
+
+void readline_move_along(struct readline_type *readline, enum keys found_key)
+{
+    switch(found_key) {
+    case left_arrow:
+        if(readline->cursor_pos > 0) {
+            putchar('\b');
+            fflush(stdout);
+            --readline->cursor_pos;
+        }
+        break;
+    case right_arrow:
+        if(readline->cursor_pos <= readline->last_element_index) {
+            putchar(readline->arr[readline->cursor_pos]);
+            fflush(stdout);
+            ++readline->cursor_pos;
+        }
+        break;
+    default:
+        ;
+    }
+}
+
+void readline_character_deletion(struct readline_type *readline)
+{
+    char *begin_arr;
+    int size;
+
+    if(readline->cursor_pos > 0) {
+        putchar('\b');
+        fflush(stdout);
+        begin_arr = readline->arr + readline->cursor_pos;
+        size = readline->last_element_index - readline->cursor_pos + 1;
+        memmove(begin_arr-1, begin_arr, size);
+        readline->arr[readline->last_element_index] = ' ';
+        readline_reprint_modified_part(readline, readline->cursor_pos - 1);
+        --readline->last_element_index;
+        --readline->cursor_pos;
+    }
+}
-- 
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