From 0ac23b651bb8b4f8f117e3061044eab173ef6d33 Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom@tomsmeding.com>
Date: Sun, 14 Jul 2024 17:53:28 +0200
Subject: weerklank

---
 src/weerklank.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 src/weerklank.c

diff --git a/src/weerklank.c b/src/weerklank.c
new file mode 100644
index 0000000..3092b3a
--- /dev/null
+++ b/src/weerklank.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+
+#include "util/map.h"
+#include "util/versie.h"
+
+static void usage(FILE *f) {
+  fprintf(f,
+      "Gebruik: weerklank [-nehV] [touwtje]...\n"
+      "\n"
+      "Exporteer de touwtjes.\n"
+      "\n"
+      "  -n    Voeg geen nieuwe regel toe\n"
+      "  -e    Ontleed terugslagontsnappingen\n"
+      "  -h    Toon deze hulptekst\n"
+      "  -V    Toon versienummer\n");
+}
+
+struct options {
+  bool nonewline;
+  bool unescape;
+};
+
+// Returns pointer to argument array containing the file names
+static char** parse_options(int argc, char **argv, struct options *opts) {
+  int opt;
+  while ((opt = getopt(argc, argv, "nehV")) != -1) {
+    switch (opt) {
+      case 'n':
+        opts->nonewline = true;
+        break;
+
+      case 'e':
+        opts->unescape = true;
+        break;
+
+      case 'h':
+        usage(stdout);
+        exit(0);
+
+      case 'V':
+        drukkedoos_print_versie(stdout, "weerklank");
+        exit(0);
+
+      case '?':
+        usage(stderr);
+        exit(1);
+    }
+  }
+
+  return argv + optind;
+}
+
+static const char lowercase_escapes[] = "\a\b\0\0\e\f\0\0\0\0\0\0\0\n\0\0\0\r\0\t\0\v\0\0\0\0";
+
+static int fromhexdigit(char c) {
+  if ('0' <= c && c <= '9') return c - '0';
+  if ('a' <= c && c <= 'f') return c - 'a' + 10;
+  if ('A' <= c && c <= 'F') return c - 'A' + 10;
+  return -1;
+}
+
+int entry_weerklank(int argc, char **argv) {
+  struct options opts = {0};
+
+  char **args = parse_options(argc, argv, &opts);
+
+  for (int i = 0; args[i]; i++) {
+    if (i != 0) putchar(' ');
+
+    if (!opts.unescape) fputs(args[i], stdout);
+    else for (int j = 0; args[i][j]; j++) {
+      if (args[i][j] != '\\') putchar(args[i][j]);
+      else if ('a' <= args[i][j+1] && args[i][j+1] <= 'z'
+                 && lowercase_escapes[args[i][j+1] - 'a'] != '\0') {
+        putchar(lowercase_escapes[args[i][j+1] - 'a']);
+        j++;
+      } else if (args[i][j+1] == '0') {
+        char n = 0;
+        int len = 0;
+        while (isdigit(args[i][j+1 + len+1]) && len < 3)
+          n = 8 * n + (args[i][j+1 + ++len] - '0');
+        putchar(n);
+        j += 1 + len;
+      } else if (args[i][j+1] == 'x') {
+        int n1, n2;
+        if ((n1 = fromhexdigit(args[i][j+2])) == -1) fputs("\\x", stdout);
+        else if ((n2 = fromhexdigit(args[i][j+3])) == -1) { putchar(n1); j += 2; }
+        else { putchar(16 * n1 + n2); j += 3; }
+      } else putchar('\\');
+    }
+  }
+
+  if (!opts.nonewline) putchar('\n');
+
+  return 0;
+}
-- 
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