[PATCH 1/5] keyboard input: simplify code, no logic changes

[Denys Vlasenko <vda linux googlemail com>]

This change slightly simplifies and rearranges the code
in get_key_code(), reduces indentation levels there,
adds a few comments. The logic remains the same.

This is a preparatory patch for subsequent changes.

Signed-off-by: Denys Vlasenko <vda linux googlemail com>
---
 lib/tty/key.c |  126 ++++++++++++++++++++++++++++----------------------------
 1 files changed, 63 insertions(+), 63 deletions(-)

diff --git a/lib/tty/key.c b/lib/tty/key.c
index f050202..d2142fa 100644
--- a/lib/tty/key.c
+++ b/lib/tty/key.c
@@ -1847,7 +1847,7 @@ get_key_code (int no_delay)
                 pending_keys = NULL;
                 seq_append = NULL;
             }
-            if ((d == ESC_CHAR) && (pending_keys != NULL))
+            else if (d == ESC_CHAR)
             {
                 d = ALT (*pending_keys++);
                 goto check_pend;
@@ -1928,49 +1928,12 @@ get_key_code (int no_delay)
             this = keys->child;
         }
     }
+
     while (this != NULL)
     {
         if (c == this->ch)
         {
-            if (this->child)
-            {
-                if (!push_char (c))
-                {
-                    pending_keys = seq_buffer;
-                    goto pend_send;
-                }
-                parent = this;
-                this = this->child;
-                if (parent->action == MCKEY_ESCAPE && old_esc_mode)
-                {
-                    if (no_delay)
-                    {
-                        GET_TIME (esctime);
-                        if (this == NULL)
-                        {
-                            /* Shouldn't happen */
-                            fputs ("Internal error\n", stderr);
-                            exit (EXIT_FAILURE);
-                        }
-                        goto nodelay_try_again;
-                    }
-                    esctime.tv_sec = -1;
-                    c = xgetch_second ();
-                    if (c == -1)
-                    {
-                        pending_keys = seq_append = NULL;
-                        this = NULL;
-                        return ESC_CHAR;
-                    }
-                }
-                else
-                {
-                    if (no_delay)
-                        goto nodelay_try_again;
-                    c = tty_lowlevel_getch ();
-                }
-            }
-            else
+            if (!this->child)
             {
                 /* We got a complete match, return and reset search */
                 int code;
@@ -1980,36 +1943,73 @@ get_key_code (int no_delay)
                 this = NULL;
                 return correct_key_code (code);
             }
-        }
-        else
-        {
-            if (this->next != NULL)
-                this = this->next;
-            else
+            /* No match yet, but it may be a prefix for a valid seq */
+
+            if (!push_char (c))
             {
-                if ((parent != NULL) && (parent->action == MCKEY_ESCAPE))
+                pending_keys = seq_buffer;
+                goto pend_send;
+            }
+            parent = this;
+            this = this->child;
+            if (parent->action == MCKEY_ESCAPE && old_esc_mode)
+            {
+                if (no_delay)
+                {
+                    GET_TIME (esctime);
+                    if (this == NULL)
+                    {
+                        /* Shouldn't happen */
+                        fputs ("Internal error\n", stderr);
+                        exit (EXIT_FAILURE);
+                    }
+                    goto nodelay_try_again;
+                }
+                esctime.tv_sec = -1;
+                c = xgetch_second ();
+                if (c == -1)
                 {
-                    /* Convert escape-digits to F-keys */
-                    if (g_ascii_isdigit (c))
-                        c = KEY_F (c - '0');
-                    else if (c == ' ')
-                        c = ESC_CHAR;
-                    else
-                        c = ALT (c);
-
                     pending_keys = seq_append = NULL;
                     this = NULL;
-                    return correct_key_code (c);
+                    return ESC_CHAR;
                 }
-                /* Did not find a match or {c} was changed in the if above,
-                   so we have to return everything we had skipped
-                 */
-                push_char (c);
-                pending_keys = seq_buffer;
-                goto pend_send;
+                continue;
             }
+            if (no_delay)
+                goto nodelay_try_again;
+            c = tty_lowlevel_getch ();
+            continue;
         }
-    }
+
+        /* c != this->ch. Try other keys with this prefix */
+        if (this->next != NULL) {
+            this = this->next;
+            continue;
+        }
+
+        /* No match found. Is it one of our ESC <key> specials? */
+        if ((parent != NULL) && (parent->action == MCKEY_ESCAPE))
+        {
+            /* Convert escape-digits to F-keys */
+            if (g_ascii_isdigit (c))
+                c = KEY_F (c - '0');
+            else if (c == ' ')
+                c = ESC_CHAR;
+            else
+                c = ALT (c);
+
+            pending_keys = seq_append = NULL;
+            this = NULL;
+            return correct_key_code (c);
+        }
+
+        /* Unknown sequence. Maybe a prefix of a longer one. Save it. */
+        push_char (c);
+        pending_keys = seq_buffer;
+        goto pend_send;
+
+    } /* while (this != NULL) */
+
     this = NULL;
     return correct_key_code (c);
 }
-- 
1.7.7.6