refactor code

pscat/Makefile

@@ -1,28 +1,22 @@
-all: pscat
+CFLAGS = -g
+RM = rm -f
+TARGETS = pscat
+
+all: $(TARGETS)
 
 clean:
-	rm -rf ../dist/pscat ../dist/pscat.tar ../dist/pscat.tar.gz pscat
+	$(RM) $(TARGETS)
 
-dist: ../dist/pscat.tar.gz
+debug:
+	$(CC) $(DEBUG) -o pscat pscat.c
 
-sane: pscat.c ../include/sysexits.h
-	$(CC) -DUSE_ASCII_H -DDONT_USE_SYSTEM_SYSEXITS -o pscat pscat.c
+%.o: %.c %.h
+	$(CC) $(CFLAGS) -c -o %.o %.c
 
-pscat: pscat.c
-	$(CC) -o pscat pscat.c
+pscat.o: psargs.h pscat.c
+	$(CC) $(CFLAGS) -DUSE_ASCII_H -DDONT_USE_SYSTEM_SYSEXITS -c -o pscat.o pscat.c
 
-../dist/pscat: pscat
-	mkdir -p ../dist/pscat.tmp/bin/ ../dist/pscat.tmp/share/man/man1/
-	cp pscat ../dist/pscat.tmp/bin/pscat
-	cp pscat.1 ../dist/pscat.tmp/share/man/man1/pscat.1
-	mv ../dist/pscat.tmp ../dist/pscat
+pscat: pscat.o psargs.o
+	$(CC) $(CFLAGS) -o pscat psargs.o pscat.o
 
-../dist/pscat.tar: ../dist/pscat
-	cd ../dist/pscat && pax -w -x ustar . >../pscat.tar.tmp
-	mv ../dist/pscat.tar.tmp ../dist/pscat.tar
-
-../dist/pscat.tar.gz: ../dist/pscat.tar
-	gzip -c <../dist/pscat.tar >../dist/pscat.tar.gz.tmp
-	mv ../dist/pscat.tar.gz.tmp ../dist/pscat.tar.gz
-
-.PHONY: all clean sane
+.PHONY: all clean

pscat/psargs.c

@@ -0,0 +1,56 @@
+#include <stddef.h>
+
+#include "psargs.h"
+
+/* Test string containing { c, '\0' } without iteration.
+ * Theoretically saves a little bit of time compared to strcmp(3). */
+#define SCMPFLAT(a, b) (*(a) != '\0' && *((a)+1) == '\0' && *(a) == (b))
+
+int
+check_arg(char **args, char l, char r){
+	enum {
+		UNINITIALIZED = 0,
+		NORMAL = 1,
+		INLPAREN = 2
+	} s;
+	int terms;
+
+	for(s = UNINITIALIZED, terms = 0; *args != NULL; ++args)
+		switch(s){
+		case UNINITIALIZED: case NORMAL:
+			if(SCMPFLAT(*args, l))
+				s = INLPAREN;
+			else
+				return 0; /* syntax error */
+			break;
+		default: /* >= INLPAREN */
+			/* decrement s if on an rparen, increment if on lparen
+			 * increment terms if on an rparen */
+			if(args[0][1] == '\0'){
+				s += (args[0][0] == l) - (args[0][0] == r);
+				terms += (args[0][0] == r && s == NORMAL);
+			}
+			break;
+		}
+
+	/* make sure nothing's open */
+	return terms * (s == NORMAL);
+}
+
+char **
+corresponding_arg(char **arg, char l, char r){
+	size_t p;
+
+	for(p = 1; p > 0;){
+		++arg;
+		/* branching here potentially saves a comparison.
+		 * this seems like the most optimal way to do this,
+		 * maybe it isn't, i don't care too much */
+		if(SCMPFLAT(*arg, l))
+			++p;
+		else if(SCMPFLAT(*arg, r))
+			--p;
+	}
+
+	return arg;
+}

pscat/psargs.h

@@ -0,0 +1,22 @@
+#if !defined _PSARGS_H
+#	define _PSARGS_H
+
+/* pscat(1) and pspipe(1) arguments are flanked by { '[', '\0' } and
+ * { ']', '\0' }. Nesting is allowed to facilitate nesting of pscat(1) and
+ * pspipe(1). This checks to make sure grouping symbols in args are balanced.
+ * args is the argv that was passed to main, incremented. l is the left
+ * grouping character (usually '[') and r is the right grouping character
+ * (usually ']').
+ * Returns 0 in the events of a syntax error or there being no arguments.
+ * Otherwise, returns the number of top-level right grouping arguments
+ * (i.e. the number of terms). */
+int check_arg(char **args, char l, char r);
+
+/* arg is the location of the argument with the left grouping symbol within
+ * argv, l is the left grouping character itself, r is the right grouping
+ * character itself.
+ * Returns the location of the argument with the corresponding left grouping
+ * symbol within argv. */
+char **corresponding_arg(char **arg, char l, char r);
+
+#endif

pscat/pscat.c

@@ -1,12 +1,14 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
 #ifndef DONT_USE_SYSTEM_SYSEXITS
 #	include <sysexits.h>
 #else
-#	include "../include/sysexits.h"
+#	include "../sysexits/sysexits.h"
 #endif /* ifndef DONT_USE_SYSTEM_SYSEXITS */
 
-#include <stdio.h>
-#include <sys/wait.h>
-#include <unistd.h>
+#include "psargs.h"
 
 static char *program_name = "pscat";
 
@@ -16,56 +18,21 @@ static char *program_name = "pscat";
 #	define L_PAREN '['
 #	define R_PAREN ']'
 #else
-#	include "../include/ascii.h"
+#	include "../ascii/ascii.h"
 #	define L_PAREN ASCII_LEFT_SQUARE_BRACKET
 #	define R_PAREN ASCII_RIGHT_SQUARE_BRACKET
 #endif /* ifndef USE_ASCII_H */
 
-/* Test string containing { c, '\0' } without iteration.
- * Theoretically saves a little bit of time compared to strcmp(3). */
-#define SCMPFLAT(a, b) (*(a) != '\0' && *((a)+1) == '\0' && *(a) == (b))
-
-/* Verifies arguments to pscat are sensible. */
-static int
-check_arg(char **argv){
-	enum {
-		UNINITIALIZED = 0,
-		NORMAL = 1,
-		INLPAREN = 2
-	} s;
-	int terms;
-
-	for(s = UNINITIALIZED, terms = 0; *argv != NULL; ++argv)
-		switch(s){
-		case UNINITIALIZED: case NORMAL:
-			if(SCMPFLAT(*argv, L_PAREN))
-				s = INLPAREN;
-			else
-				return 0; /* syntax error */
-			break;
-		default: /* >= INLPAREN */
-			if(argv[0][1] == '\0'){
-				s -= (argv[0][0] == R_PAREN);
-				terms += (argv[0][0] == R_PAREN && s == NORMAL);
-				s += (argv[0][0] == L_PAREN);
-			}
-			break;
-		}
-
-	return terms;
-}
-
 int main(int argc, char *argv[]){
 	char **psstart;
 	int child;
 	int i;
-	int p;
 	int retval;
 	int terms;
 
 	retval = 0;
 
-	if((terms = check_arg(++argv)) == 0){
+	if((terms = check_arg(++argv, L_PAREN, R_PAREN)) == 0){
 		fprintf(stderr,
 			"Usage: %s \"[\" [utility [argument...]] \"]\" ...\n",
 			argv[0] == NULL ? program_name : argv[0]
@@ -75,18 +42,8 @@ int main(int argc, char *argv[]){
 
 	/* loop starts with *argv -> the next L_PAREN */
 	for(i = 0; i < terms; ++i){
-		psstart = ++argv;
-		p = 1;
-		while(p > 0){
-			++argv;
-			/* branching here potentially saves a comparison.
-			 * this seems like the most optimal way to do this,
-			 * maybe it isn't, i don't care too much */
-			if(SCMPFLAT(*argv, L_PAREN))
-				++p;
-			else if(SCMPFLAT(*argv, R_PAREN))
-				--p;
-		}
+		psstart = argv + 1;
+		argv = corresponding_arg(argv, L_PAREN, R_PAREN);
 		/* *argv -> the corresponding R_PAREN. turn it into NULL to
 		 * terminate the argument list to send to execvp(3) */
 		*argv = NULL;