mruby · matz · Aug 18, 2026 · Aug 18, 2026 · Aug 18, 2026 · Aug 18, 2026
@@ -22,7 +22,6 @@
     cc.flags << %w(-O2 -pipe -g -feliminate-unused-debug-types)
     cc.flags << "--sysroot=#{POKY_EDISON_SYSROOT}"
     cc.compile_options = %Q[%{flags} -o "%{outfile}" -c "%{infile}"]
-    cc.defines = %w(MRB_USE_READLINE)
   end
 
   conf.cxx do |cxx|

@@ -13,7 +13,9 @@ mirb-prism (mruby interactive) is an interactive Ruby shell for mruby, using the
 
 ## Tab Completion
 
-mirb supports context-aware tab completion when built with a readline library.
+mirb supports context-aware tab completion in its built-in multi-line editor.
+The editor is used when standard input is a terminal; no external line-editing
+library is required or consulted.
 
 ### Supported Completions
 
@@ -53,30 +55,11 @@ mirb supports context-aware tab completion when built with a readline library.
   class
   ```
 
-### Readline Library Support
+### Behavior
 
-Tab completion works with:
-
-- **GNU readline** (default on Linux)
-- **libedit** (default on macOS/BSD)
-- **linenoise** (lightweight alternative)
-
-### Configuration
-
-The readline library can be configured via the `MRUBY_MIRB_READLINE` environment variable:
-
-```bash
-# Auto-detect (default)
-rake
-
-# Force specific library
-MRUBY_MIRB_READLINE=readline rake    # GNU readline
-MRUBY_MIRB_READLINE=libedit rake     # libedit
-MRUBY_MIRB_READLINE=linenoise rake   # linenoise
-
-# Disable readline (plain input mode)
-MRUBY_MIRB_READLINE=none rake
-```
+- A single match is inserted in place of the typed prefix
+- Multiple matches sharing a longer common prefix extend the input to that prefix
+- Otherwise the candidates are listed below the input line
 
 ### Notes
 

@@ -40,16 +40,6 @@ strndup(const char *s, size_t n)
 }
 #endif
 
-#ifdef MRB_USE_READLINE
-#ifndef MRB_USE_LINENOISE
-#include MRB_READLINE_HEADER
-#endif
-#endif
-
-#ifdef MRB_USE_LINENOISE
-#include <linenoise.h>
-#endif
-
 /* ============================================================
  * Core Completion Engine
  * ============================================================ */
@@ -84,7 +74,6 @@ mirb_completion_free(mirb_completion_ctx *ctx)
 
   ctx->completion_count = 0;
   ctx->completion_alloc = 0;
-  ctx->current_index = 0;
 }
 
 /* ============================================================
@@ -586,117 +575,6 @@ mirb_cleanup_completion(void)
   }
 }
 
-/* ============================================================
- * Readline/Libedit Adapter
- * ============================================================ */
-
-#ifdef MRB_USE_READLINE
-#ifndef MRB_USE_LINENOISE
-
-static char *
-mirb_readline_generator(const char *text, int state)
-{
-  (void)text;  /* text is already in match_prefix */
-
-  /* state == 0: first call, generate completions */
-  if (state == 0) {
-    mirb_completion_free(g_ctx);
-
-    /* Generate completions based on full line */
-    mirb_generate_completions(g_ctx, rl_line_buffer, rl_point);
-
-    g_ctx->current_index = 0;
-  }
-
-  /* Return next completion or NULL when done */
-  if (g_ctx->current_index < g_ctx->completion_count) {
-    char *completion = g_ctx->completions[g_ctx->current_index];
-    g_ctx->current_index++;
-
-    /* readline will free this, so duplicate */
-    return strdup(completion);
-  }
-
-  return NULL;
-}
-
-static char **
-mirb_readline_completion(const char *text, int start, int end)
-{
-  (void)start;
-  (void)end;
-
-  /* Prevent default filename completion */
-  rl_attempted_completion_over = 1;
-
-  /* Use our generator */
-  return rl_completion_matches(text, mirb_readline_generator);
-}
-
-void
-mirb_setup_readline_completion(mrb_state *mrb, mrb_ccontext *cxt)
-{
-  if (!init_completion_ctx(mrb, cxt)) return;
-
-  /* Set completion function */
-  rl_attempted_completion_function = mirb_readline_completion;
-
-  /* Configure readline behavior - include . so "obj.method" are separate words */
-  rl_basic_word_break_characters = " \t\n\"\\'`@$><=;|&{(.";
-  rl_completer_word_break_characters = " \t\n\"\\'`@$><=;|&{(.";
-}
-
-#endif
-#endif
-
-/* ============================================================
- * Linenoise Adapter
- * ============================================================ */
-
-#ifdef MRB_USE_LINENOISE
-
-static void
-mirb_linenoise_completion(const char *buf, linenoiseCompletions *lc)
-{
-  int cursor_pos = (int)strlen(buf);  /* linenoise completes at end */
-  int i, prefix_start;
-  char completion_line[1024];
-
-  /* Clear previous completions */
-  mirb_completion_free(g_ctx);
-
-  /* Generate completions */
-  mirb_generate_completions(g_ctx, buf, cursor_pos);
-
-  /* Need to build full line with completion */
-  prefix_start = cursor_pos - g_ctx->prefix_len;
-  if (prefix_start < 0) return;
-
-  /* Add each completion to linenoise */
-  for (i = 0; i < g_ctx->completion_count; i++) {
-    size_t len = strlen(g_ctx->completions[i]);
-
-    if ((size_t)prefix_start + len + 1 > sizeof(completion_line)) continue;
-
-    /* Copy line up to prefix, then the completion */
-    memcpy(completion_line, buf, prefix_start);
-    memcpy(completion_line + prefix_start, g_ctx->completions[i], len+1);
-
-    linenoiseAddCompletion(lc, completion_line);
-  }
-}
-
-void
-mirb_setup_linenoise_completion(mrb_state *mrb, mrb_ccontext *cxt)
-{
-  if (!init_completion_ctx(mrb, cxt)) return;
-
-  /* Set completion callback */
-  linenoiseSetCompletionCallback(mirb_linenoise_completion);
-}
-
-#endif
-
 /* ============================================================
  * Custom Editor Adapter
  * ============================================================ */

@@ -17,7 +17,7 @@
  *
  * Architecture:
  * - Core engine is library-agnostic
- * - Adapters for readline/libedit and linenoise
+ * - Adapter for the built-in multi-line editor
  * - Context detection based on input line analysis
  * - Safe evaluation of receiver expressions
  *
@@ -58,7 +58,6 @@ typedef struct mirb_completion_ctx {
   char **completions;       /* Array of completion strings */
   int completion_count;     /* Number of completions */
   int completion_alloc;     /* Allocated size */
-  int current_index;        /* For generator pattern (readline) */
 } mirb_completion_ctx;
 
 /* Core Completion Engine Interface */
@@ -100,21 +99,9 @@ mrb_value mirb_eval_receiver(mrb_state *mrb, const char *receiver_expr, mrb_ccon
 /* Check if in file completion context */
 mrb_bool mirb_in_file_context(const char *line, int quote_pos);
 
-/* Cleanup completion context (shared by all adapters) */
+/* Cleanup completion context */
 void mirb_cleanup_completion(void);
 
-/* Readline/Libedit adapter setup */
-#ifdef MRB_USE_READLINE
-#ifndef MRB_USE_LINENOISE
-void mirb_setup_readline_completion(mrb_state *mrb, mrb_ccontext *cxt);
-#endif
-#endif
-
-/* Linenoise adapter setup */
-#ifdef MRB_USE_LINENOISE
-void mirb_setup_linenoise_completion(mrb_state *mrb, mrb_ccontext *cxt);
-#endif
-
 /* Custom editor adapter */
 void mirb_setup_editor_completion(mrb_state *mrb, mrb_ccontext *cxt);