From 805da5c405847547f19a8e7967c4e32abc05b790 Mon Sep 17 00:00:00 2001
From: Thomas Voss <mail@thomasvoss.com>
Date: Thu, 5 Sep 2024 23:09:30 +0200
Subject: Perform line continuation in non-interactive mode only

---
 src/lexer.l | 18 +++++++++++++++---
 src/main.c  | 11 +++++++++--
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/lexer.l b/src/lexer.l
index 8715932..3b4a2e2 100644
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -1,10 +1,17 @@
 %{
 #include <err.h>
+#include <stdbool.h>
 #include <stdlib.h>
 
 #include "parser.h"
 #include "pinocchio.h"
 
+#define YY_USER_INIT                                                           \
+	do {                                                                       \
+		if (!interactive)                                                      \
+			BEGIN(linecont);                                                   \
+	} while (false);
+
 #define YY_USER_ACTION                                                         \
 	do {                                                                       \
 		yylloc.first_column = yylloc.last_column;                              \
@@ -16,8 +23,9 @@
 			} else                                                             \
 				yylloc.last_column++;                                          \
 		}                                                                      \
-	} while (0);
+	} while (false);
 
+extern bool interactive;
 extern const char *current_file;
 %}
 
@@ -28,6 +36,7 @@ extern const char *current_file;
 ws [ \t]
 
 %x error
+%s linecont
 
 %%
 
@@ -43,8 +52,11 @@ ws [ \t]
 \\     { return '\\';  }
 \n     { return EOL;   }
 
-	/* Allow line-continuation when the newline is suffixed by a backslash */
-\n{ws}*\\ ;
+	/* Allow line-continuation when the newline is suffixed by a
+	   backslash, but not in interactive mode!  Interactive usage should
+	   have this functionality disabled so that you get instant feedback
+	   after hitting the enter key. */
+<linecont>\n{ws}*\\ ;
 
 [a-zA-Z] {
 	yylval.ch = *yytext;
diff --git a/src/main.c b/src/main.c
index 3e48469..81fe189 100644
--- a/src/main.c
+++ b/src/main.c
@@ -40,10 +40,10 @@ typedef enum {
 } bool_style_t;
 
 static int rv;
-static bool interactive;
 static bool_style_t bflag = BS_BINARY;
 static tbl_style_t tflag = TS_UNSET;
 
+bool interactive;
 const char *current_file;
 
 static void astprocess_cli(asts_t);
@@ -70,7 +70,6 @@ main(int argc, char **argv)
 {
 	argv[0] = basename(argv[0]);
 	setlocale(LC_ALL, "");
-	interactive = isatty(STDIN_FILENO);
 
 	int opt;
 	const char *sflag = NULL;
@@ -131,6 +130,14 @@ usage:
 	if (sflag != NULL && argc != 0)
 		goto usage;
 
+	/* We’re considered to be interactive if stdin is a TTY (meaning it’s
+	   not a pipe or something) and no files have been specified on the
+	   command-line.  We should also take care to check for -s, because
+	   that implies non-interactive usage.  We intentionally consider
+	   ‘interactive’ usage with the command-line argument ‘-’ to not be
+	   interactive. */
+	interactive = sflag == NULL && argc == 0 && isatty(STDIN_FILENO);
+
 	if (argc == 0) {
 		if (sflag != NULL &&
 			(yyin = fmemopen((char *)sflag, strlen(sflag), "r")) == NULL)
-- 
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