From 8f182d5db075f4f4b939725065596f49bbd0d0d4 Mon Sep 17 00:00:00 2001
From: David Phillips <david@sighup.nz>
Date: Sun, 4 Aug 2019 00:20:08 +1200
Subject: lex: empty file is equivalent to EOL

lex() returning NULL is used to convey an error case but having not allocated
any tokens in the case of an empty input file isn't an error case. This patch
causes lex to treat an empty token stream after successfully examining a file
as just a single EOL token. This is a fair approximation of an empty file for
this assembler's purposes, and results in the correct behaviour of an empty
output file.
---
 assembler.c                      | 11 +++++++++++
 lex.c                            |  7 +++++++
 test/emul/001-empty.asm          |  0
 test/full-pipeline/010-empty.asm |  0
 4 files changed, 18 insertions(+)
 create mode 100644 test/emul/001-empty.asm
 create mode 100644 test/full-pipeline/010-empty.asm

diff --git a/assembler.c b/assembler.c
index 9ffdb85..7ae699d 100644
--- a/assembler.c
+++ b/assembler.c
@@ -7,6 +7,9 @@
 #include "instruction.h"
 #include "output/output_bin.h"
 
+//#define DEBUG
+#include "debug.h"
+
 void print_help(const char *argv0)
 {
 	fprintf(stderr, "Syntax: %s <in.asm> <out.bin>\n", argv0);
@@ -45,12 +48,14 @@ int main(int argc, char **argv)
 		perror("fopen");
 		return error_ret;
 	}
+	debug("Opened fin\n");
 
 	if ((fout = fopen(path_out, "wb")) == NULL) {
 		fprintf(stderr, "Error opening %s: ", path_out);
 		perror("fopen");
 		return error_ret;
 	}
+	debug("Opened fout\n");
 /****/
 	struct token *tokens = NULL;
 	size_t tok_count = 0;
@@ -58,6 +63,8 @@ int main(int argc, char **argv)
 	if ((tokens = lex(path_in, fin, &tok_count)) == NULL)
 		return error_ret;
 
+	debug("Lexed.\n");
+
 	/* FIXME package these things into `tok_result`, `parse_result` etc */
 	struct instruction *insts;
 	size_t insts_count;
@@ -66,6 +73,8 @@ int main(int argc, char **argv)
 	if ((ret = parse(path_in, fin, &labels, &labels_count, tokens, tok_count, &insts, &insts_count)))
 		return error_ret && ret;
 
+	debug("Parsed.\n");
+
 	/* FIXME insert pass for sanity checking identifiers, sizes of values */
 
 	/* FIXME insert optional pass for optimisation */
@@ -73,5 +82,7 @@ int main(int argc, char **argv)
 	if ((ret = output_bin(fout, labels, labels_count, insts, insts_count)))
 		return error_ret && ret;
 
+	debug("Output.\n");
+
 	return 0;
 }
diff --git a/lex.c b/lex.c
index 6fe78b3..949425e 100644
--- a/lex.c
+++ b/lex.c
@@ -406,6 +406,13 @@ struct token* lex(const char *filename_local, FILE *fin, size_t *len)
 		return NULL;
 	}
 
+	/* no tokens? just an EOL then */
+	if (tokens_count == 0) {
+		struct token eol = {0};
+		lex_eol(&eol);
+		add_token(eol);
+	}
+
 	*len = tokens_count;
 	return tokens;
 }
diff --git a/test/emul/001-empty.asm b/test/emul/001-empty.asm
new file mode 100644
index 0000000..e69de29
diff --git a/test/full-pipeline/010-empty.asm b/test/full-pipeline/010-empty.asm
new file mode 100644
index 0000000..e69de29
-- 
cgit v1.1