From 2f4cb88d5c60f725323739300bb49dfa8923e7d5 Mon Sep 17 00:00:00 2001
From: Albert Cervin <albert@acervin.com>
Date: Wed, 2 Nov 2022 22:20:04 +0100
Subject: =?UTF-8?q?=F0=9F=8E=89=20And=20so=20it=20begins?=
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---
 src/command.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 src/command.c

(limited to 'src/command.c')

diff --git a/src/command.c b/src/command.c
new file mode 100644
index 0000000..4b233b2
--- /dev/null
+++ b/src/command.c
@@ -0,0 +1,66 @@
+#include "command.h"
+
+#include <stdlib.h>
+
+struct commands command_list_create(uint32_t capacity) {
+  return (struct commands){
+      .commands = calloc(capacity, sizeof(struct hashed_command)),
+      .ncommands = 0,
+      .capacity = capacity,
+  };
+}
+
+void command_list_destroy(struct commands *commands) {
+  free(commands->commands);
+  commands->ncommands = 0;
+  commands->capacity = 0;
+}
+
+uint32_t hash_command_name(const char *name) {
+  unsigned long hash = 5381;
+  int c;
+
+  while ((c = *name++))
+    hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+
+  return hash;
+}
+
+uint32_t register_command(struct commands *commands, struct command *command) {
+  if (commands->ncommands == commands->capacity) {
+    commands->capacity *= 2;
+    commands->commands = realloc(
+        commands->commands, sizeof(struct hashed_command) * commands->capacity);
+  }
+
+  uint32_t hash = hash_command_name(command->name);
+  commands->commands[commands->ncommands] =
+      (struct hashed_command){.command = command, .hash = hash};
+
+  ++commands->ncommands;
+  return hash;
+}
+
+void register_commands(struct commands *command_list, struct command *commands,
+                       uint32_t ncommands) {
+  for (uint32_t ci = 0; ci < ncommands; ++ci) {
+    register_command(command_list, &commands[ci]);
+  }
+}
+
+struct command *lookup_command(struct commands *command_list,
+                               const char *name) {
+  uint32_t needle = hash_command_name(name);
+  return lookup_command_by_hash(command_list, needle);
+}
+
+struct command *lookup_command_by_hash(struct commands *commands,
+                                       uint32_t hash) {
+  for (uint32_t ci = 0; ci < commands->ncommands; ++ci) {
+    if (commands->commands[ci].hash == hash) {
+      return commands->commands[ci].command;
+    }
+  }
+
+  return NULL;
+}
-- 
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