Introduce multiline strings using triple double-quoting

Signed-off-by: Maxime Soulé <btik-git@scoubidou.com>

doc/manual/ctwm.1.adoc

@@ -208,8 +208,24 @@ user-defined menus (containing functions to be invoked or
 commands to be executed).
 
 Variable names and keywords are case-insensitive.  Strings must be
-surrounded by double quote characters (e.g. ``blue'') and are
-case-sensitive.  A pound sign (#) outside of a string causes the
+surrounded by double quote characters (e.g. "blue") and are
+case-sensitive. A string can contain newline characters (useful for
+`f.exec` or `f.dynmenu`), but multiline strings are better achieved
+using triple quoting as in:
+------
+f.dynmenu """
+cat <<EOF
+"$(hostname)" f.title
+"*$(date)"    !"daemon xterm"
+EOF
+"""
+------
+In double quoted strings, classic escape sequences are recognized
+(`\b`, `\f`, `\n`, `\r`, `\t`, octal `\nnn`, hexadecimal `\0xnn` or
+`\xnn`, `\"`, `\'` and `\\`). In multiline strings, no escape
+sequences are allowed.
+
+A pound sign (&#35;) outside of a string or a multiline strings causes the
 remainder of the line in which the character appears to be treated as
 a comment.
 

gram.y

@@ -97,7 +97,7 @@ int yylex(void);
 %token <num> MONITOR_LAYOUT
 %token <num> RPLAY_SOUNDS
 %token <num> FORCE_FOCUS
-%token <ptr> STRING
+%token <ptr> STRING MLSTRING
 
 %type <ptr> string
 %type <num> action button number signed_number keyaction full fullkey
@@ -1129,6 +1129,7 @@ string		: STRING		{ char *ptr = strdup($1);
 					  RemoveDQuote(ptr);
 					  $$ = ptr;
 					}
+		| MLSTRING		{ $$ = DupUnquoteMultilineString($1); }
 		;
 
 number		: NUMBER		{ $$ = $1; }

lex.l

@@ -49,6 +49,7 @@
 %}
 
 string				\"([^"]|\\.)*\"
+mlstring			\"\"\"([^\"]+|\"[^\"]+|\"\"[^\"]+)*\"\"\"
 number				[0-9]+
 
  /* Requires flex 2.5.1 (28Mar95) */
@@ -82,6 +83,7 @@ number				[0-9]+
 "!"				{ yylval.num = F_EXEC; return FSKEYWORD; }
 
 {string}			{ yylval.ptr = yytext; return STRING; }
+{mlstring}			{ yylval.ptr = yytext; return MLSTRING; }
 {number}			{ sscanf(yytext, "%d", &yylval.num);
 				  return NUMBER; }
 \#[^\n]*\n			{;}

parse_menu.c

@@ -14,6 +14,17 @@ extern int (*twmInputFunc)(void);
 extern int yylex(void);
 extern char *yytext;
 
+static char *
+strdupunquote(char *s, bool multiline)
+{
+	if(multiline) {
+		return DupUnquoteMultilineString(s);
+	}
+	s = strdup(s);
+	RemoveDQuote(s);
+	return s;
+}
+
 static bool
 ParseMenuEntry(MenuRoot *menu)
 {
@@ -50,9 +61,9 @@ ParseMenuEntry(MenuRoot *menu)
 				step = STEP_ERROR;
 				break;
 
+			case MLSTRING:
 			case STRING:
-				str = strdup(yylval.ptr);
-				RemoveDQuote(str);
+				str = strdupunquote(yylval.ptr, token == MLSTRING);
 				switch(step) {
 					case STEP_START:
 						label = str;

parse_yacc.c

@@ -8,6 +8,7 @@
 #include "ctwm.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <strings.h>
 
@@ -132,6 +133,19 @@ void RemoveDQuote(char *str)
 	*o = '\0';
 }
 
+char *DupUnquoteMultilineString(char *str)
+{
+	char *ret;
+	int len;
+
+	str += 3;
+	len = strlen(str) - 3;
+	ret = malloc(len + 1);
+	memcpy(ret, str, len);
+	ret[len] = '\0';
+	return ret;
+}
+
 MenuRoot *GetRoot(char *name, char *fore, char *back, bool dynamic)
 {
 	MenuRoot *tmp;

parse_yacc.h

@@ -8,6 +8,7 @@ void yyerror(char *s);
 
 void InitGramVariables(void);
 void RemoveDQuote(char *str);
+char *DupUnquoteMultilineString(char *str);
 
 MenuRoot *GetRoot(char *name, char *fore, char *back, bool dynamic);