From 83965726d5757ad4a68c8e2e756e6a31d59a614d Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Sat, 7 Mar 2020 22:17:23 -0800
Subject: Allow multiple inputs to main compiler process

This way, we can implement -include in the driver by just passing
an additional input to the compiler.
---
 cc.h   |  9 +++++++--
 main.c | 12 +++++++++---
 pp.c   | 14 ++++++--------
 scan.c | 38 +++++++++++++++++++++++++-------------
 4 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/cc.h b/cc.h
index 62c9780..3e6eecf 100644
--- a/cc.h
+++ b/cc.h
@@ -1,3 +1,5 @@
+#include <stdio.h>
+
 struct func;
 
 enum tokenkind {
@@ -374,10 +376,13 @@ _Noreturn void error(const struct location *, const char *, ...);
 
 /* scan */
 
-int scanfrom(const char *file);
+void scanfrom(const char *, FILE *);
+void scanopen(void);
 void scan(struct token *);
 
-void ppinit(const char *);
+/* preprocessor */
+
+void ppinit(void);
 
 void next(void);
 _Bool peek(int);
diff --git a/main.c b/main.c
index e1b3324..2cf5bcb 100644
--- a/main.c
+++ b/main.c
@@ -37,12 +37,18 @@ main(int argc, char *argv[])
 
 	targinit(target);
 
-	if (argc > 1)
-		usage();
 	if (output && !freopen(output, "w", stdout))
 		fatal("open %s:", output);
 
-	ppinit(argv[0]);
+	if (argc) {
+		while (argc--)
+			scanfrom(argv[argc], NULL);
+		scanopen();
+	} else {
+		scanfrom("<stdin>", stdin);
+	}
+
+	ppinit();
 	if (pponly) {
 		while (tok.kind != TEOF) {
 			tokprint(&tok);
diff --git a/pp.c b/pp.c
index 8db0848..a92ee26 100644
--- a/pp.c
+++ b/pp.c
@@ -9,6 +9,12 @@
 
 static struct token pending;
 
+void
+ppinit(void)
+{
+	next();
+}
+
 static void
 keyword(struct token *tok)
 {
@@ -92,14 +98,6 @@ keyword(struct token *tok)
 	}
 }
 
-void
-ppinit(const char *file)
-{
-	if (scanfrom(file) < 0)
-		fatal("open %s:", file);
-	next();
-}
-
 static void
 nextinto(struct token *t)
 {
diff --git a/scan.c b/scan.c
index 5464cde..ef2a2ca 100644
--- a/scan.c
+++ b/scan.c
@@ -409,20 +409,11 @@ again:
 	}
 }
 
-int
-scanfrom(const char *name)
+void
+scanfrom(const char *name, FILE *file)
 {
 	struct scanner *s;
-	FILE *file;
 
-	if (name) {
-		file = fopen(name, "r");
-		if (!file)
-			return -1;
-	} else {
-		file = stdin;
-		name = "<stdin>";
-	}
 	s = xmalloc(sizeof(*s));
 	s->file = file;
 	s->buf.str = NULL;
@@ -433,9 +424,28 @@ scanfrom(const char *name)
 	s->loc.line = 1;
 	s->loc.col = 0;
 	s->next = scanner;
+	if (file)
+		nextchar(s);
 	scanner = s;
-	nextchar(s);
-	return 0;
+}
+
+void
+scanopen(void)
+{
+	if (!scanner->file) {
+		scanner->file = fopen(scanner->loc.file, "r");
+		if (!scanner->file)
+			fatal("open %s:", scanner->loc.file);
+		nextchar(scanner);
+	}
+}
+
+static void
+scanclose(void)
+{
+	fclose(scanner->file);
+	free(scanner->buf.str);
+	free(scanner);
 }
 
 void
@@ -446,7 +456,9 @@ scan(struct token *t)
 		t->kind = scankind(scanner);
 		if (t->kind != TEOF || !scanner->next)
 			break;
+		scanclose();
 		scanner = scanner->next;
+		scanopen();
 	}
 	if (scanner->usebuf) {
 		t->lit = bufget(&scanner->buf);
-- 
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