On 29/09/14 21:20, Werner LEMBERG wrote:
>
>> I've refactored the appropriate code, in src/roff/troff/input.cpp,
>> with a view to accommodating this; see patch attached. While I've
>> not yet progressed any implementation for PDF handling, I have
>> indicated the point at which it should be invoked. Okay to commit,
>> thus far?
>
> This is very nice, thanks! For my taste, the comments are a bit
> excessive, but I guess this is probably only me who thinks so :-)
I've always favoured a verbose commenting style, since I learned to
write FORTRAN-66, way back in the early 1970s. Today, with my failing
60+ year old memory, I really appreciate the value of this, when I come
back to code 6 months or so after I wrote it, and find that I cannot
remember how it was supposed to work :-)
> Some comments, mainly regarding formatting:
>
> + while ((context = bounding_box_args()) == NULL
> + && get_line(DSC_LINE_MAX_ENFORCE) > 0)
> + ;
>
> Please say
>
> while ((context = bounding_box_args()) == NULL
> && get_line(DSC_LINE_MAX_ENFORCE) > 0)
> ;
Okay.
> + while (*context == '\x20' || *context == '\t')
> + context++;
Hmm. I don't know how that crept in ...
> Please say
>
> while (*context == '\x20' || *context == '\t')
> context++;
This is how it *looked* in my working file copy, but there's one tab in
amongst a string of spaces there -- I must have somehow managed to
override vim's normal tab insertion on that line. The extra '+' flag,
in the patch file, pushed it over by an extra tab stop, and I missed it
when I cast my eye over the patch. It should be fixed, in the updated
patch attached.
> + status = (context_args("(atend)", context) == NULL)
> + ? llx = lly = urx = ury = PSBB_RANGE_IS_BAD
> + : PSBB_RANGE_AT_END;
>
> Please say
>
> status = (context_args("(atend)", context) == NULL)
> ? llx = lly = urx = ury = PSBB_RANGE_IS_BAD
> : PSBB_RANGE_AT_END;
Okay.
> + register size_t len = strlen(tag);
>
> Given that recent versions of clang emit warnings if it encounters the
> `register' keyword, and given that this keyword has no effect for
> about 20 years, please don't use it:
Done, but are you sure about the lack of effect? (I seem to recall
having observed a benefit, quite recently, in assembly code generated by
GCC-4.8.2).
--
Regards,
Keith.
# HG changeset patch
# Parent 2a6fa75a470a9cc8af750dd4c73c7ddd9fb633d2
Refactor .psbb request handling code.
* src/roff/troff/input.cpp (do_ps_file): Reimplement it, using...
(psbb_locator): ...this new locally declared and implemented class;
its constructor replaces all `do_ps_file()' capability, delegating
to other class methods, as appropriate.
(assign_registers): Encapsulate it, as a `psbb_locator' method.
(ps_get_line): Likewise, also renaming it to become...
(get_line): ...this class method; its internally defined `lastc'
static variable also becomes a non-static class member variable.
(PSBB_RANGE_IS_BAD, PSBB_RANGE_IS_SET, PSBB_RANGE_AT_END): New
manifest constants; define them. They are now used by...
(parse_bounding_box): ...this function, now also encapsulated as
a `psbb_locator' class method, to convey parsing status.
(bounding_box): Struct obsoleted by `psbb_locator'; delete it.
(ps_bbox_request): Delegate to `psbb_locator'.
diff --git a/src/roff/troff/input.cpp b/src/roff/troff/input.cpp
--- a/src/roff/troff/input.cpp
+++ b/src/roff/troff/input.cpp
@@ -5998,97 +5998,267 @@ void pipe_source()
#endif /* not POPEN_MISSING */
}
}
// .psbb
-
+//
+// Extract bounding box limits from PostScript file, and assign
+// them to the following four gtroff registers:--
+//
static int llx_reg_contents = 0;
static int lly_reg_contents = 0;
static int urx_reg_contents = 0;
static int ury_reg_contents = 0;
-struct bounding_box {
- int llx, lly, urx, ury;
-};
-
-/* Parse the argument to a %%BoundingBox comment. Return 1 if it
-contains 4 numbers, 2 if it contains (atend), 0 otherwise. */
-
-int parse_bounding_box(char *p, bounding_box *bb)
-{
- if (sscanf(p, "%d %d %d %d",
- &bb->llx, &bb->lly, &bb->urx, &bb->ury) == 4)
- return 1;
- else {
- /* The Document Structuring Conventions say that the numbers
- should be integers. Unfortunately some broken applications
- get this wrong. */
- double x1, x2, x3, x4;
- if (sscanf(p, "%lf %lf %lf %lf", &x1, &x2, &x3, &x4) == 4) {
- bb->llx = (int)x1;
- bb->lly = (int)x2;
- bb->urx = (int)x3;
- bb->ury = (int)x4;
- return 1;
- }
- else {
- for (; *p == ' ' || *p == '\t'; p++)
- ;
- if (strncmp(p, "(atend)", 7) == 0) {
- return 2;
- }
- }
- }
- bb->llx = bb->lly = bb->urx = bb->ury = 0;
- return 0;
-}
-
-// This version is an adaptation of that in psrm.cpp
-
-cset white_space("\n\r \t");
+// Manifest constants to specify the status of bounding box range
+// acquisition; (note that PSBB_RANGE_IS_BAD is also suitable for
+// assignment as a default ordinate property value).
+//
+#define PSBB_RANGE_IS_BAD 0
+#define PSBB_RANGE_IS_SET 1
+#define PSBB_RANGE_AT_END 2
// Maximum input line length, for DSC conformance, and options to
// control how it will be enforced; caller should select either of
// DSC_LINE_MAX_IGNORED, to allow partial line collection spread
// across multiple calls, or DSC_LINE_MAX_ENFORCE, to truncate
// excess length lines at the DSC limit.
//
// Note that DSC_LINE_MAX_CHECKED is reserved for internal use by
-// ps_get_line(), and should not be specified by any caller; also,
-// handling of DSC_LINE_MAX_IGNORED is currently unimplemented.
+// ps_locator::get_line(), and should not be specified in any call;
+// also, handling of DSC_LINE_MAX_IGNORED, as a get_line() option,
+// is currently unimplemented.
//
#define DSC_LINE_MAX 255
#define DSC_LINE_MAX_IGNORED -1
#define DSC_LINE_MAX_ENFORCE 0
#define DSC_LINE_MAX_CHECKED 1
-// ps_get_line(): collect an input record from a PostScript file.
+// Input characters to be considered as white space, when reading
+// PostScript file comments.
+//
+cset white_space("\n\r \t");
+
+// Class psbb_locator
+//
+// This locally declared and implemented class provides the methods
+// to be used for retrieval of bounding box properties from a specified
+// PostScript or PDF file.
+//
+class psbb_locator
+{
+ public:
+ // Only the class constructor is exposed publicly; instantiation of
+ // a class object will retrieve the requisite bounding box properties
+ // from the specified file, and assign them to gtroff registers.
+ //
+ psbb_locator(const char *);
+
+ private:
+ // Member variables, shared by class method functions.
+ //
+ FILE *fp;
+ const char *filename;
+ char buf[2 + DSC_LINE_MAX];
+ int llx, lly, urx, ury;
+
+ // CRLF handling hook, for get_line() function.
+ //
+ int lastc;
+
+ // Private method functions facilitate implementation of
+ // the class constructor.
+ //
+ int get_line(int);
+ inline bool get_header_comment(void);
+ inline const char *context_args(const char *);
+ inline const char *context_args(const char *, const char *);
+ inline const char *bounding_box_args(void);
+ int parse_bounding_box(const char *);
+ inline void assign_registers(void);
+ inline int skip_to_trailer(void);
+};
+
+// psbb_locator class constructor.
+//
+psbb_locator::psbb_locator(const char *fname):
+filename(fname), llx(0), lly(0), urx(0), ury(0), lastc(EOF)
+{
+ // PS files might contain non-printable characters, such as ^Z
+ // and CRs not followed by an LF, so open them in binary mode.
+ //
+ fp = include_search_path.open_file_cautious(filename, 0, FOPEN_RB);
+ if (fp) {
+ // After successfully opening the file, acquire the first
+ // line, whence we may determine the file format...
+ //
+ if (get_line(DSC_LINE_MAX_ENFORCE) == 0)
+ //
+ // ...except in the case of an empty file, which we are
+ // unable to process further.
+ //
+ error("`%1' is empty", filename);
+
+# if 0
+ else if (context_args("%PDF-")) {
+ // TODO: PDF files specify a /MediaBox, as the equivalent
+ // of a BoundingBox; we must implement handler for this.
+ }
+# endif
+
+ else if (context_args("%!PS-Adobe-")) {
+ //
+ // PostScript files -- strictly, we expect EPS -- should
+ // specify a %%BoundingBox comment; locate it, initially
+ // expecting to find it in the comments header...
+ //
+ const char *context = NULL;
+ while ((context == NULL) && get_header_comment()) {
+ if ((context = bounding_box_args()) != NULL) {
+
+ // When the "%%BoundingBox" comment is found, it may simply
+ // specify the bounding box property values, or it may defer
+ // assignment to a similar trailer comment...
+ //
+ int status = parse_bounding_box(context);
+ if (status == PSBB_RANGE_AT_END) {
+ //
+ // ...in which case we must locate the trailer, and search
+ // for the appropriate specification within it.
+ //
+ if (skip_to_trailer() > 0) {
+ while ((context = bounding_box_args()) == NULL
+ && get_line(DSC_LINE_MAX_ENFORCE) > 0)
+ ;
+ if (context != NULL) {
+ //
+ // When we find a bounding box specification here...
+ //
+ if ((status = parse_bounding_box(context)) == PSBB_RANGE_AT_END)
+ //
+ // ...we must ensure it is not a further attempt to defer
+ // assignment to a trailer, (which we are already parsing).
+ //
+ error("`(atend)' not allowed in trailer of `%1'", filename);
+ }
+ }
+ else
+ // The trailer could not be found, so there is no context in
+ // which a trailing %%BoundingBox comment might be located.
+ //
+ context = NULL;
+ }
+ if (status == PSBB_RANGE_IS_BAD) {
+ //
+ // This arises when we found a %%BoundingBox comment, but
+ // we were unable to extract a valid set of range values from
+ // it; all we can do is diagnose this.
+ //
+ error("the arguments to the %%%%BoundingBox comment in `%1' are bad",
+ filename);
+ }
+ }
+ }
+ if (context == NULL)
+ //
+ // Conversely, this arises when no value specifying %%BoundingBox
+ // comment has been found, in any appropriate location...
+ //
+ error("%%%%BoundingBox comment not found in `%1'", filename);
+ }
+ else
+ // ...while this indicates that there was no appropriate file format
+ // identifier, on the first line of the input file.
+ //
+ error("`%1' does not conform to the Document Structuring Conventions",
+ filename);
+
+ // Regardless of success or failure of bounding box property acquisition,
+ // we did successfully open an input file, so we must now close it...
+ //
+ fclose(fp);
+ }
+ else
+ // ...but in this case, we did not successfully open any input file.
+ //
+ error("can't open `%1': %2", filename, strerror(errno));
+
+ // Irrespective of whether or not we were able to successfully acquire the
+ // bounding box properties, we ALWAYS update the associated gtroff registers.
+ //
+ assign_registers();
+}
+
+// psbb_locator::parse_bounding_box()
+//
+// Parse the argument to a %%BoundingBox comment, returning:
+// PSBB_RANGE_IS_SET if it contains four numbers,
+// PSBB_RANGE_AT_END if it contains "(atend)", or
+// PSBB_RANGE_IS_BAD otherwise.
+//
+int psbb_locator::parse_bounding_box(const char *context)
+{
+ // The Document Structuring Conventions say that the numbers
+ // should be integers.
+ //
+ int status = PSBB_RANGE_IS_SET;
+ if (sscanf(context, "%d %d %d %d", &llx, &lly, &urx, &ury) != 4) {
+ //
+ // Unfortunately some broken applications get this wrong;
+ // try to parse them as doubles instead...
+ //
+ double x1, x2, x3, x4;
+ if (sscanf(context, "%lf %lf %lf %lf", &x1, &x2, &x3, &x4) == 4) {
+ llx = (int)x1;
+ lly = (int)x2;
+ urx = (int)x3;
+ ury = (int)x4;
+ }
+ else {
+ // ...but if we can't parse four numbers, skip over any
+ // initial white space...
+ //
+ while (*context == '\x20' || *context == '\t')
+ context++;
+
+ // ...before checking for "(atend)", and setting the
+ // appropriate exit status accordingly.
+ //
+ status = (context_args("(atend)", context) == NULL)
+ ? llx = lly = urx = ury = PSBB_RANGE_IS_BAD
+ : PSBB_RANGE_AT_END;
+ }
+ }
+ return status;
+}
+
+// ps_locator::get_line()
+//
+// Collect an input record from a PostScript or PDF file.
//
// Inputs:
// buf pointer to caller's input buffer.
// fp FILE stream pointer, whence input is read.
// filename name of input file, (for diagnostic use only).
// dscopt DSC_LINE_MAX_ENFORCE or DSC_LINE_MAX_IGNORED.
//
// Returns the number of input characters stored into caller's
// buffer, or zero at end of input stream.
//
-// FIXME: Currently, ps_get_line() always scans an entire line of
+// FIXME: Currently, get_line() always scans an entire line of
// input, but returns only as much as will fit in caller's buffer;
// the return value is always a positive integer, or zero, with no
// way of indicating to caller, that there was more data than the
// buffer could accommodate. A future enhancement could mitigate
// this, returning a negative value in the event of truncation, or
// even allowing for piecewise retrieval of excessively long lines
// in successive reads; (this may be necessary to properly support
// DSC_LINE_MAX_IGNORED, which is currently unimplemented).
//
-static
-int ps_get_line(char *buf, FILE *fp, const char* filename, int dscopt)
+int psbb_locator::get_line(int dscopt)
{
int c, count = 0;
- static int lastc = EOF;
do {
// Collect input characters into caller's buffer, until we
// encounter a line terminator, or end of file...
//
while (((c = getc(fp)) != '\n') && (c != '\r') && (c != EOF)) {
@@ -6138,126 +6308,156 @@ int ps_get_line(char *buf, FILE *fp, con
//
buf[count] = '\0';
return count;
}
-inline void assign_registers(int llx, int lly, int urx, int ury)
+// psbb_locator::context_args()
+//
+// Inputs:
+// tag literal text to be matched at start of input line
+//
+// Returns a pointer to the trailing substring of the current
+// input line, following an initial substring matching the "tag"
+// argument, or NULL if "tag" is not matched.
+//
+inline const char *psbb_locator::context_args(const char *tag)
+{
+ return context_args(tag, buf);
+}
+
+// psbb_locator::context_args()
+//
+// Overloaded variant of the preceding function, operating on
+// an alternative input buffer, (which may represent a terminal
+// substring of the psbb_locator's primary input line buffer).
+//
+// Inputs:
+// tag literal text to be matched at start of buffer
+// buf pointer to text to be checked for "tag" match
+//
+// Returns a pointer to the trailing substring of the specified
+// text buffer, following an initial substring matching the "tag"
+// argument, or NULL if "tag" is not matched.
+//
+inline const char *psbb_locator::context_args(const char *tag, const char *buf)
+{
+ size_t len = strlen(tag);
+ return (strncmp(tag, buf, len) == 0) ? buf + len : NULL;
+}
+
+// psbb_locator::bounding_box_args()
+//
+// Returns a pointer to the arguments string, within the current
+// input line, when this represents a PostScript "%%BoundingBox:"
+// comment, or NULL otherwise.
+//
+inline const char *psbb_locator::bounding_box_args(void)
+{
+ return context_args("%%BoundingBox:");
+}
+
+// psbb_locator::assign_registers()
+//
+// Copies the bounding box properties established within the
+// class object, to the associated gtroff registers.
+//
+inline void psbb_locator::assign_registers(void)
{
llx_reg_contents = llx;
lly_reg_contents = lly;
urx_reg_contents = urx;
ury_reg_contents = ury;
}
-void do_ps_file(FILE *fp, const char* filename)
-{
- bounding_box bb;
- int bb_at_end = 0;
- char buf[2 + DSC_LINE_MAX];
- llx_reg_contents = lly_reg_contents =
- urx_reg_contents = ury_reg_contents = 0;
- if (!ps_get_line(buf, fp, filename, DSC_LINE_MAX_ENFORCE)) {
- error("`%1' is empty", filename);
- return;
- }
- if (strncmp("%!PS-Adobe-", buf, 11) != 0) {
- error("`%1' is not conforming to the Document Structuring Conventions",
- filename);
- return;
- }
- while (ps_get_line(buf, fp, filename, DSC_LINE_MAX_ENFORCE) != 0) {
- // in header comments, `%X' (`X' any printable character except
- // whitespace) is possible too
- if (buf[0] == '%') {
- if (strncmp(buf + 1, "%EndComments", 12) == 0)
- break;
- if (white_space(buf[1]))
- break;
- }
- else
- break;
- if (strncmp(buf + 1, "%BoundingBox:", 13) == 0) {
- int res = parse_bounding_box(buf + 14, &bb);
- if (res == 1) {
- assign_registers(bb.llx, bb.lly, bb.urx, bb.ury);
- return;
- }
- else if (res == 2) {
- bb_at_end = 1;
- break;
- }
- else {
- error("the arguments to the %%%%BoundingBox comment in `%1' are bad",
- filename);
- return;
- }
- }
- }
- if (bb_at_end) {
- long offset;
- int last_try = 0;
- // in the trailer, the last BoundingBox comment is significant
- for (offset = 512; !last_try; offset *= 2) {
- int had_trailer = 0;
- int got_bb = 0;
- if (offset > 32768 || fseek(fp, -offset, 2) == -1) {
- last_try = 1;
- if (fseek(fp, 0L, 0) == -1)
- break;
- }
- while (ps_get_line(buf, fp, filename, DSC_LINE_MAX_ENFORCE) != 0) {
- if (buf[0] == '%' && buf[1] == '%') {
- if (!had_trailer) {
- if (strncmp(buf + 2, "Trailer", 7) == 0)
- had_trailer = 1;
- }
- else {
- if (strncmp(buf + 2, "BoundingBox:", 12) == 0) {
- int res = parse_bounding_box(buf + 14, &bb);
- if (res == 1)
- got_bb = 1;
- else if (res == 2) {
- error("`(atend)' not allowed in trailer of `%1'", filename);
- return;
- }
- else {
- error("the arguments to the %%%%BoundingBox comment in `%1' are bad",
- filename);
- return;
- }
- }
- }
- }
- }
- if (got_bb) {
- assign_registers(bb.llx, bb.lly, bb.urx, bb.ury);
- return;
- }
- }
- }
- error("%%%%BoundingBox comment not found in `%1'", filename);
-}
-
+// psbb_locator::get_header_comment()
+//
+// Fetch a line of PostScript input; return true if it complies with
+// the formatting requirements for header comments, and it is not an
+// "%%EndComments" line; otherwise return false.
+//
+inline bool psbb_locator::get_header_comment(void)
+{
+ return
+ // The first necessary requirement, for returning true,
+ // is that the input line is not empty, (i.e. not EOF).
+ //
+ get_line(DSC_LINE_MAX_ENFORCE) != 0
+
+ // In header comments, `%X' (`X' any printable character
+ // except whitespace) is also acceptable.
+ //
+ && (buf[0] == '%') && !white_space(buf[1])
+
+ // Finally, the input line must not say "%%EndComments".
+ //
+ && context_args("%%EndComments") == NULL;
+}
+
+// psbb_locator::skip_to_trailer()
+//
+// Reposition the PostScript input stream, such that the next get_line()
+// will retrieve the first line, if any, following a "%%Trailer" comment;
+// returns a positive integer value if the "%%Trailer" comment is found,
+// or zero if it is not.
+//
+inline int psbb_locator::skip_to_trailer(void)
+{
+ // Begin by considering a chunk of the input file starting 512 bytes
+ // before its end, and search it for a "%%Trailer" comment; if none is
+ // found, incrementally double the chunk size while it remains within
+ // a 32768L byte range, and search again...
+ //
+ for (ssize_t offset = 512L; offset > 0L; offset <<= 1) {
+ int status, failed;
+ if ((offset > 32768L) || ((failed = fseek(fp, -offset, SEEK_END)) != 0))
+ //
+ // ...ultimately resetting the offset to zero, and simply seeking
+ // to the start of the file, to terminate the cycle and do a "last
+ // ditch" search of the entire file, if any backward seek fails, or
+ // if we reach the arbitrary 32768L byte range limit.
+ //
+ failed = fseek(fp, offset = 0L, SEEK_SET);
+
+ // Following each successful seek...
+ //
+ if (!failed) {
+ //
+ // ...perform a search by reading lines from the input stream...
+ //
+ do { status = get_line(DSC_LINE_MAX_ENFORCE);
+ //
+ // ...until we either exhaust the available stream data, or
+ // we have located a "%%Trailer" comment line.
+ //
+ } while ((status != 0) && (context_args("%%Trailer") == NULL));
+ if (status > 0)
+ //
+ // We found the "%%Trailer" comment, so we may immediately
+ // return, with the stream positioned appropriately...
+ //
+ return status;
+ }
+ }
+ // ...otherwise, we report that no "%%Trailer" comment was found.
+ //
+ return 0;
+}
+
+// ps_bbox_request()
+//
+// Handle the .psbb request.
+//
void ps_bbox_request()
{
symbol nm = get_long_name(1);
if (nm.is_null())
skip_line();
else {
while (!tok.newline() && !tok.eof())
tok.next();
errno = 0;
- // PS files might contain non-printable characters, such as ^Z
- // and CRs not followed by an LF, so open them in binary mode.
- FILE *fp = include_search_path.open_file_cautious(nm.contents(),
- 0, FOPEN_RB);
- if (fp) {
- do_ps_file(fp, nm.contents());
- fclose(fp);
- }
- else
- error("can't open `%1': %2", nm.contents(), strerror(errno));
+ psbb_locator do_ps_file(nm.contents());
tok.next();
}
}
const char *asciify(int c)
