From e24c054839170a1c08d130120ca2a5ea3c913198 Mon Sep 17 00:00:00 2001
From: Evan Welsh <contact@evanwelsh.com>
Date: Tue, 29 Jun 2021 01:07:13 -0700
Subject: modules: Implement console.clear()

---
 util/console.cpp | 28 ++++++++++++++++++++++++++++
 util/console.h   |  2 ++
 2 files changed, 30 insertions(+)

(limited to 'util')

diff --git a/util/console.cpp b/util/console.cpp
index 49bf77e1..5489ab6b 100644
--- a/util/console.cpp
+++ b/util/console.cpp
@@ -3,14 +3,35 @@
 
 #include <config.h>
 
+#include <stdio.h>
+
 #ifdef HAVE_UNISTD_H
 #    include <unistd.h>
 #elif defined(_WIN32)
 #    include <io.h>
 #endif
 
+#include <glib.h>
+
 #include "util/console.h"
 
+/**
+ * ANSI escape code sequences to manipulate terminals.
+ *
+ * See
+ * https://en.wikipedia.org/wiki/ANSI_escape_code#CSI_(Control_Sequence_Introducer)_sequences
+ */
+namespace ANSICode {
+/**
+ * ANSI escape code sequence to clear the terminal screen.
+ *
+ * Combination of 0x1B (Escape) and the sequence nJ where n=2,
+ * n=2 clears the entire display instead of only after the cursor.
+ */
+constexpr const char CLEAR_SCREEN[] = "\x1b[2J";
+
+}  // namespace ANSICode
+
 #ifdef HAVE_UNISTD_H
 const int stdin_fd = STDIN_FILENO;
 const int stdout_fd = STDOUT_FILENO;
@@ -34,3 +55,10 @@ bool gjs_console_is_tty(int fd) {
     return false;
 #endif
 }
+
+bool gjs_console_clear() {
+    if (stdout_fd < 0 || !g_log_writer_supports_color(stdout_fd))
+        return false;
+
+    return fputs(ANSICode::CLEAR_SCREEN, stdout) > 0 && fflush(stdout) > 0;
+}
diff --git a/util/console.h b/util/console.h
index d8acd5ed..df27f305 100644
--- a/util/console.h
+++ b/util/console.h
@@ -24,6 +24,8 @@ extern const int stderr_fd;
 GJS_USE
 bool gjs_console_is_tty(int fd);
 
+bool gjs_console_clear(void);
+
 G_END_DECLS
 
 #endif  // UTIL_CONSOLE_H_
-- 
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