add fold

fold.c

@@ -0,0 +1,99 @@
+/* See LICENSE file for copyright and license details. */
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "text.h"
+#include "util.h"
+
+static void fold(FILE *, const char *, long);
+static void foldline(const char *, long);
+
+static bool bflag = false;
+static bool sflag = false;
+
+int
+main(int argc, char *argv[])
+{
+	char c, *end;
+	long width = 80;
+	FILE *fp;
+
+	while((c = getopt(argc, argv, "bsw:")) != -1)
+		switch(c) {
+		case 'b':
+			bflag = true;
+			break;
+		case 's':
+			sflag = true;
+			break;
+		case 'w':
+			width = strtol(optarg, &end, 0);
+			if(*end != '\0')
+				eprintf("%s: not a number\n", optarg);
+			break;
+		default:
+			exit(EXIT_FAILURE);
+		}
+	if(optind == argc)
+		fold(stdin, "<stdin>", width);
+	else for(; optind < argc; optind++) {
+		if(!(fp = fopen(argv[optind], "r")))
+			eprintf("fopen %s:", argv[optind]);
+		fold(fp, argv[optind], width);
+		fclose(fp);
+	}
+	return EXIT_SUCCESS;
+}
+
+void
+fold(FILE *fp, const char *str, long width)
+{
+	char *buf = NULL;
+	size_t size = 0;
+
+	while(afgets(&buf, &size, fp))
+		foldline(buf, width);
+	free(buf);
+}
+
+void
+foldline(const char *str, long width)
+{
+	bool space;
+	long col, i, j, n;
+
+	for(i = n = 0; str[i] && str[i] != '\n'; i = n) {
+		space = false;
+		for(j = i, col = 0; str[j] && col <= width; j++) {
+			if(!UTF8_POINT(str[j]) && !bflag)
+				continue;
+			if(sflag && isspace(str[j])) {
+				space = true;
+				n = j+1;
+			}
+			else if(!space)
+				n = j;
+
+			if(!bflag && iscntrl(str[j]))
+				switch(str[j]) {
+				case '\b':
+					col--;
+					break;
+				case '\r':
+					col = 0;
+					break;
+				case '\t':
+					col += (col+1) % 8;
+					break;
+				}
+			else
+				col++;
+		}
+		if(fwrite(&str[i], 1, n-i, stdout) != n-i)
+			eprintf("<stdout>: write error:");
+		if(str[n])
+			putchar('\n');
+	}
+}