Implement two new conditional operators `F <name>' and `S <name>'

which check whether <name> is a valid font or style, respectively.

* src/libs/libgroff/font.cpp (text_file): Add `silent' member.
(text_file::text_file): Updated.
(text_file::error): Don't emit message if `silent' is set.
(font::load_font): Add optional third argument (which is directly
passed to `load'.
(font::load): Add optional second argument to check the header of
a font only, without emitting warning or error messages.
* src/include/font.h (font): Updated.

* src/roff/troff/input.cpp (do_if_request): Implement `S' and `F'
conditionals.
* src/roff/troff/node.cpp (mount_font_no_translate): Add optional
fourth argument to check a font without mounting.
(check_font, check_style): New functions.
* src/roff/troff/node.h: Updated.

* man/groff_diff.man, man/groff.man, NEWS, doc/groff.texinfo:
Updated.

10 files changed, 161 insertions, 48 deletions

diff --git a/ChangeLog b/ChangeLog
index f81de2a8..541a8b75 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,28 @@
-2004-06-27  Werner LEMBERG  <wl@gnu.org
+2004-06-29  Werner LEMBERG  <wl@gnu.org>
+
+	Implement two new conditional operators `F <name>' and `S <name>'
+	which check whether <name> is a valid font or style, respectively.
+
+	* src/libs/libgroff/font.cpp (text_file): Add `silent' member.
+	(text_file::text_file): Updated.
+	(text_file::error): Don't emit message if `silent' is set.
+	(font::load_font): Add optional third argument (which is directly
+	passed to `load'.
+	(font::load): Add optional second argument to check the header of
+	a font only, without emitting warning or error messages.
+	* src/include/font.h (font): Updated.
+
+	* src/roff/troff/input.cpp (do_if_request): Implement `S' and `F'
+	conditionals.
+	* src/roff/troff/node.cpp (mount_font_no_translate): Add optional
+	fourth argument to check a font without mounting.
+	(check_font, check_style): New functions.
+	* src/roff/troff/node.h: Updated.
+
+	* man/groff_diff.man, man/groff.man, NEWS, doc/groff.texinfo:
+	Updated.
+
+2004-06-27  Werner LEMBERG  <wl@gnu.org>
 
 	Implement new string-valued register `.sty' to return the current
 	style name.
diff --git a/NEWS b/NEWS
index 84df4f0c..e1f0cab5 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,11 @@ Troff
 o A new read-only, string-valued register `.sty' returns the name of the
   current style.
 
+o Two new conditional operators `F <name>' and `S <name>' have been added.
+  `F' is true if a font <name> exists.  `S' is true if a style <name> has
+  been registered.
+  
+
 Gxditview
 ---------
 
diff --git a/doc/groff.texinfo b/doc/groff.texinfo
index f5fdce39..612a4405 100644
--- a/doc/groff.texinfo
+++ b/doc/groff.texinfo
@@ -8282,8 +8282,12 @@ the current environment.
 @cindex @code{fspecial} request, and font translations
 @cindex @code{fp} request, and font translations
 @cindex @code{sty} request, and font translations
+@cindex @code{if} request, and font translations
+@cindex @code{ie} request, and font translations
+@cindex @code{while} request, and font translations
 Translate font@tie{}@var{f} to font@tie{}@var{g}.  Whenever a font
-named@tie{}@var{f} is referred to in a @code{\f} escape sequence, or in the
+named@tie{}@var{f} is referred to in a @code{\f} escape sequence,
+in the @code{F} and @code{S} conditional operators, or in the
 @code{ft}, @code{ul}, @code{bd}, @code{cs}, @code{tkf},
 @code{special}, @code{fspecial}, @code{fp}, or @code{sty} requests,
 font@tie{}@var{g} is used.  If @var{g} is missing or equal to@tie{}@var{f}
@@ -10208,6 +10212,17 @@ conditional operator is a misnomer since it tests names of output
 glyphs.}; @var{g} is either an @acronym{ASCII} character or a special
 character (@code{\(@var{gg}} or @code{\[@var{ggg}]}); the condition
 is also true if @var{g} has been defined by the @code{char} request.
+
+@item F @var{font}
+True if a font named @var{font} exists.  @var{font} is handled as if it was
+opened with the @code{ft} request (this is, font translation and styles are
+applied), without actually mounting it.
+
+This test doesn't load the complete font but only its header to verify
+its validity.
+
+@item S @var{style}
+True if style @var{style} has been registered.  Font translation is applied.
 @end table
 
 Note that these operators can't be combined with other operators like
diff --git a/man/groff.man b/man/groff.man
index 0e08c332..6bd261d8 100644
--- a/man/groff.man
+++ b/man/groff.man
@@ -2,7 +2,7 @@
 .ig
 groff.man
 
-Last update: 27 Jun 2004
+Last update: 29 Jun 2004
 
 This file is part of groff, the GNU roff type-setting system.
 
@@ -1015,6 +1015,17 @@ True if there is a register named
 Formatter is
 .BR troff .
 .
+.TPx
+.BI F font
+True if there exists a font named
+.IR font .
+.
+.TPx
+.BI S style
+True if a style named
+.I style
+has been registered.
+.
 .RE
 .PD
 .
diff --git a/man/groff_diff.man b/man/groff_diff.man
index b3ebc940..19e9a600 100644
--- a/man/groff_diff.man
+++ b/man/groff_diff.man
@@ -3,7 +3,7 @@
 .ig
 groff_diff.man
 
-Last update : 27 Jun 2004
+Last update : 29 Jun 2004
 
 This file is part of groff, the GNU roff type-setting system.
 It is the source of the man-page groff_diff(7).
@@ -1440,7 +1440,11 @@ Whenever a font named
 .I f
 is referred to in an
 .B \[rs]f
-escape sequence, or in the
+escape sequence, in the
+.B F
+and
+.B S
+conditional operators, or in the
 .BR ft ,
 .BR ul ,
 .BR bd ,
@@ -3079,6 +3083,26 @@ has been defined by the
 .B char
 request.
 .
+.TP
+.BI .if\ F f
+True if font
+.I f
+exists.
+.
+.B f
+is handled as if it was opened with the
+.B ft
+request (this is, font translation and styles are applied), without
+actually mounting it.
+.
+.TP
+.BI .if\ S s
+True if style
+.I s
+has been registered.
+.
+Font translation is applied.
+.
 .P
 The
 .B tr
@@ -3095,16 +3119,11 @@ Example:
 .ne 6v+\n(.Vu
 .ft CB
 .nf
-.Text .de foo
-.Text .  nop Hello, I'm `foo'.
-.Text .  nop I will now define `bar'.
+.Text .if t \[rs]{\[rs]
 .Text .  de bar
 .Text .    nop Hello, I'm `bar'.
 .Text .  .
-.Text .  nop Done.
-.Text ..
-.Text .foo
-.Text .bar
+.Text .\[rs]}
 .fi
 .
 .
diff --git a/src/include/font.h b/src/include/font.h
index 3d46138e..987cf6cc 100644
--- a/src/include/font.h
+++ b/src/include/font.h
@@ -57,7 +57,7 @@ public:
 
   static int scan_papersize(const char *, const char **, double *, double *);
 
-  static font *load_font(const char *, int *not_found = 0);
+  static font *load_font(const char *, int * = 0, int = 0);
   static void command_line_font_dir(const char *path);
   static FILE *open_file(const char *name, char **pathp);
   static int load_desc();
@@ -117,5 +117,5 @@ private:
 					   const char *file, int lineno);
 protected:
   font(const char *);
-  int load(int *not_found = 0);
+  int load(int * = 0, int = 0);
 };
diff --git a/src/libs/libgroff/font.cpp b/src/libs/libgroff/font.cpp
index 7883fdf6..6af6c30b 100644
--- a/src/libs/libgroff/font.cpp
+++ b/src/libs/libgroff/font.cpp
@@ -71,6 +71,7 @@ struct text_file {
   int lineno;
   int size;
   int skip_comments;
+  int silent;
   char *buf;
   text_file(FILE *fp, char *p);
   ~text_file();
@@ -82,7 +83,7 @@ struct text_file {
 };
 
 text_file::text_file(FILE *p, char *s) 
-: fp(p), path(s), lineno(0), size(0), skip_comments(1), buf(0)
+: fp(p), path(s), lineno(0), size(0), skip_comments(1), silent(0), buf(0)
 {
 }
 
@@ -141,7 +142,8 @@ void text_file::error(const char *format,
 		      const errarg &arg2,
 		      const errarg &arg3)
 {
-  error_with_file_and_line(path, lineno, format, arg1, arg2, arg3);
+  if (!silent)
+    error_with_file_and_line(path, lineno, format, arg1, arg2, arg3);
 }
 
 
@@ -479,10 +481,10 @@ void font::copy_entry(int new_index, int old_index)
   ch_index[new_index] = ch_index[old_index];
 }
 
-font *font::load_font(const char *s, int *not_found)
+font *font::load_font(const char *s, int *not_found, int head_only)
 {
   font *f = new font(s);
-  if (!f->load(not_found)) {
+  if (!f->load(not_found, head_only)) {
     delete f;
     return 0;
   }
@@ -557,7 +559,7 @@ again:
 // If the font can't be found, then if not_found is non-NULL, it will be set
 // to 1 otherwise a message will be printed.
 
-int font::load(int *not_found)
+int font::load(int *not_found, int head_only)
 {
   char *path;
   FILE *fp;
@@ -570,6 +572,7 @@ int font::load(int *not_found)
   }
   text_file t(fp, path);
   t.skip_comments = 1;
+  t.silent = head_only;
   char *p;
   for (;;) {
     if (!t.next()) {
@@ -638,6 +641,8 @@ int font::load(int *not_found)
     else
       break;
   }
+  if (head_only)
+    return 1;
   char *command = p;
   int had_charset = 0;
   t.skip_comments = 0;
diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
index 62be5844..2bcb579c 100644
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -5272,6 +5272,24 @@ int do_if_request()
     result = character_exists(ci, curenv);
     tok.next();
   }
+  else if (c == 'F') {
+    tok.next();
+    symbol nm = get_long_name(1);
+    if (nm.is_null()) {
+      skip_alternative();
+      return 0;
+    }
+    result = check_font(curenv->get_family()->nm, nm);
+  }
+  else if (c == 'S') {
+    tok.next();
+    symbol nm = get_long_name(1);
+    if (nm.is_null()) {
+      skip_alternative();
+      return 0;
+    }
+    result = check_style(nm);
+  }
   else if (tok.space())
     result = 0;
   else if (tok.delimiter()) {
diff --git a/src/roff/troff/node.cpp b/src/roff/troff/node.cpp
index 02624a3a..5a2cf7f6 100644
--- a/src/roff/troff/node.cpp
+++ b/src/roff/troff/node.cpp
@@ -5391,7 +5391,8 @@ static symbol get_font_translation(symbol nm)
 
 dictionary font_dictionary(50);
 
-static int mount_font_no_translate(int n, symbol name, symbol external_name)
+static int mount_font_no_translate(int n, symbol name, symbol external_name,
+				   int check_only = 0)
 {
   assert(n >= 0);
   // We store the address of this char in font_dictionary to indicate
@@ -5401,7 +5402,9 @@ static int mount_font_no_translate(int n, symbol name, symbol external_name)
   void *p = font_dictionary.lookup(external_name);
   if (p == 0) {
     int not_found;
-    fm = font::load_font(external_name.contents(), &not_found);
+    fm = font::load_font(external_name.contents(), &not_found, check_only);
+    if (check_only)
+      return fm != 0;
     if (!fm) {
       if (not_found)
 	warning(WARN_FONT, "can't find font `%1'", external_name.contents());
@@ -5418,6 +5421,8 @@ static int mount_font_no_translate(int n, symbol name, symbol external_name)
   }
   else
     fm = (font*)p;
+  if (check_only)
+    return 1;
   if (n >= font_table_size) {
     if (n - font_table_size > 1000) {
       error("font position too much larger than first unused position");
@@ -5443,6 +5448,19 @@ int mount_font(int n, symbol name, symbol external_name)
   return mount_font_no_translate(n, name, external_name);
 }
 
+int check_font(symbol fam, symbol name)
+{
+  if (check_style(name))
+    name = concat(fam, name);
+  return mount_font_no_translate(0, name, name, 1);
+}
+
+int check_style(symbol s)
+{
+  int i = symbol_fontno(s);
+  return i < 0 ? 0 : font_table[i]->is_style();
+}
+
 void mount_style(int n, symbol name)
 {
   assert(n >= 0);
diff --git a/src/roff/troff/node.h b/src/roff/troff/node.h
index 7baef298..31c58581 100644
--- a/src/roff/troff/node.h
+++ b/src/roff/troff/node.h
@@ -51,8 +51,8 @@ struct node {
   node *next;
   node *last;
   node();
-  node(node *n);
-  node *add_char(charinfo *c, environment *, hunits *widthp, int *spacep);
+  node(node *);
+  node *add_char(charinfo *, environment *, hunits *, int *);
 
   virtual ~node();
   virtual node *copy() = 0;
@@ -67,7 +67,7 @@ struct node {
   virtual int merge_space(hunits, hunits, hunits);
   virtual vunits vertical_width();
   virtual node *last_char_node();
-  virtual void vertical_extent(vunits *min, vunits *max);
+  virtual void vertical_extent(vunits *, vunits *);
   virtual int character_type();
   virtual void set_vertical_size(vertical_size *);
   virtual int ends_sentence();
@@ -81,9 +81,7 @@ struct node {
   virtual void spread_space(int *, hunits *);
   virtual void freeze_space();
   virtual void is_escape_colon();
-  virtual breakpoint *get_breakpoints(hunits width, int nspaces,
-				      breakpoint *rest = 0,
-				      int is_inner = 0);
+  virtual breakpoint *get_breakpoints(hunits, int, breakpoint * = 0, int = 0);
   virtual int nbreaks();
   virtual void split(int, node **, node **);
   virtual hyphenation_type get_hyphenation_type();
@@ -172,8 +170,7 @@ public:
   void is_escape_colon();
   void spread_space(int *, hunits *);
   void tprint(troff_output_file *);
-  breakpoint *get_breakpoints(hunits width, int nspaces, breakpoint *rest = 0,
-			      int is_inner = 0);
+  breakpoint *get_breakpoints(hunits, int, breakpoint * = 0, int = 0);
   int nbreaks();
   void split(int, node **, node **);
   void ascii_print(ascii_output_file *);
@@ -222,8 +219,7 @@ public:
   void asciify(macro *);
   const char *type();
   int force_tprint();
-  breakpoint *get_breakpoints(hunits width, int nspaces, breakpoint *rest = 0,
-			      int is_inner = 0);
+  breakpoint *get_breakpoints(hunits, int, breakpoint * = 0, int = 0);
   int nbreaks();
   void split(int, node **, node **);
   int merge_space(hunits, hunits, hunits);
@@ -235,7 +231,7 @@ public:
 class diverted_space_node : public node {
 public:
   vunits n;
-  diverted_space_node(vunits d, node *p = 0);
+  diverted_space_node(vunits, node * = 0);
   node *copy();
   int reread(int *);
   int same(node *);
@@ -247,7 +243,7 @@ class diverted_copy_file_node : public node {
   symbol filename;
 public:
   vunits n;
-  diverted_copy_file_node(symbol s, node *p = 0);
+  diverted_copy_file_node(symbol, node * = 0);
   node *copy();
   int reread(int *);
   int same(node *);
@@ -388,7 +384,7 @@ public:
 class zero_width_node : public node {
   node *n;
 public:
-  zero_width_node(node *gn);
+  zero_width_node(node *);
   ~zero_width_node();
   node *copy();
   void tprint(troff_output_file *);
@@ -397,7 +393,7 @@ public:
   int force_tprint();
   void append(node *);
   int character_type();
-  void vertical_extent(vunits *min, vunits *max);
+  void vertical_extent(vunits *, vunits *);
 };
 
 class left_italic_corrected_node : public node {
@@ -492,8 +488,8 @@ class suppress_node : public node {
   int  image_id;
 public:
   suppress_node(int, int);
-  suppress_node(symbol f, char p, int id);
-  suppress_node(int, int, symbol f, char p, int id);
+  suppress_node(symbol, char, int);
+  suppress_node(int, int, symbol, char, int);
   node *copy();
   void tprint(troff_output_file *);
   hunits width();
@@ -501,7 +497,7 @@ public:
   const char *type();
   int force_tprint();
 private:
-  void put(troff_output_file *out, const char *s);
+  void put(troff_output_file *, const char *);
 };
 
 struct hvpair {
@@ -530,15 +526,15 @@ public:
 };
 
 class charinfo;
-node *make_node(charinfo *ci, environment *);
+node *make_node(charinfo *, environment *);
 int character_exists(charinfo *, environment *);
 
-int same_node_list(node *n1, node *n2);
-node *reverse_node_list(node *n);
+int same_node_list(node *, node *);
+node *reverse_node_list(node *);
 void delete_node_list(node *);
 node *copy_node_list(node *);
 
-int get_bold_fontno(int f);
+int get_bold_fontno(int);
 
 inline hyphen_list::hyphen_list(unsigned char code, hyphen_list *p)
 : hyphen(0), breakable(0), hyphenation_code(code), next(p)
@@ -546,9 +542,11 @@ inline hyphen_list::hyphen_list(unsigned char code, hyphen_list *p)
 }
 
 extern void read_desc();
-extern int mount_font(int n, symbol, symbol = NULL_SYMBOL);
-extern void mount_style(int n, symbol);
-extern int is_good_fontno(int n);
+extern int mount_font(int, symbol, symbol = NULL_SYMBOL);
+extern int check_font(symbol, symbol);
+extern int check_style(symbol);
+extern void mount_style(int, symbol);
+extern int is_good_fontno(int);
 extern int symbol_fontno(symbol);
 extern int next_available_font_position();
 extern void init_size_table(int *);
@@ -559,7 +557,7 @@ class output_file {
 public:
   output_file();
   virtual ~output_file();
-  virtual void trailer(vunits page_length);
+  virtual void trailer(vunits);
   virtual void flush() = 0;
   virtual void transparent_char(unsigned char) = 0;
   virtual void print_line(hunits x, vunits y, node *n,
@@ -567,7 +565,7 @@ public:
   virtual void begin_page(int pageno, vunits page_length) = 0;
   virtual void copy_file(hunits x, vunits y, const char *filename) = 0;
   virtual int is_printing() = 0;
-  virtual void put_filename(const char *filename);
+  virtual void put_filename(const char *);
   virtual void on();
   virtual void off();
 #ifdef COLUMN
@@ -581,7 +579,7 @@ extern char *pipe_command;
 
 extern output_file *the_output;
 extern void init_output();
-int in_output_page_list(int n);
+int in_output_page_list(int);
 
 class font_family {
   int *map;