#LyX 2.2 created this file. For more info see http://www.lyx.org/ \lyxformat 503 \begin_document \begin_header \origin /systemlyxdir/examples/ \textclass article \use_default_options false \begin_modules noweb \end_modules \maintain_unincluded_children false \language english \language_package default \inputencoding default \fontencoding global \font_roman "default" "default" \font_sans "default" "default" \font_typewriter "default" "default" \font_math "auto" "auto" \font_default_family default \use_non_tex_fonts false \font_sc false \font_osf false \font_sf_scale 100 100 \font_tt_scale 100 100 \graphics default \default_output_format default \output_sync 0 \bibtex_command default \index_command default \paperfontsize default \spacing single \use_hyperref false \papersize default \use_geometry false \use_package amsmath 0 \use_package amssymb 0 \use_package cancel 0 \use_package esint 0 \use_package mathdots 1 \use_package mathtools 0 \use_package mhchem 1 \use_package stackrel 0 \use_package stmaryrd 0 \use_package undertilde 0 \cite_engine basic \cite_engine_type default \biblio_style plain \use_bibtopic false \use_indices false \paperorientation portrait \suppress_date false \justification true \use_refstyle 0 \index Index \shortcut idx \color #008000 \end_index \secnumdepth 3 \tocdepth 3 \paragraph_separation indent \paragraph_indentation default \quotes_language english \papercolumns 1 \papersides 1 \paperpagestyle default \tracking_changes false \output_changes false \html_math_output 0 \html_css_as_file 0 \html_be_strict false \end_header \begin_body \begin_layout Title \SpecialCharNoPassThru LyX and Literate Programming \begin_inset Newline newline \end_inset An example program \end_layout \begin_layout Author Edmar Wienskoski Jr. \begin_inset Newline newline \end_inset edmar-w-jr@technologist.com \begin_inset Foot status collapsed \begin_layout Plain Layout Modified by Bernard Michael Hurley bernardh@westherts.ac.uk \threehyphens - Don't blame Edmar for any errors that have crept in! \end_layout \end_inset \end_layout \begin_layout Abstract \series bold Note: \series default This example program is provided for educational use only. The functionality in this C program has been superceded by the equivalent Python code in \emph on examples/listerrors.lyx \emph default which should be installed in the \SpecialCharNoPassThru LyX scripts directory. \end_layout \begin_layout Date \begin_inset ERT status collapsed \begin_layout Plain Layout \backslash today \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset CommandInset toc LatexCommand tableofcontents \end_inset \end_layout \begin_layout Section Introduction \end_layout \begin_layout Standard After typesetting a document, \SpecialCharNoPassThru LyX scans the \SpecialCharNoPassThru LaTeX log file looking for errors. For each error found, the line number is obtained and a error box is displayed in the \SpecialCharNoPassThru LyX screen at that position. \end_layout \begin_layout Standard To use this feature to view compilation errors while working with literate documents, we need a program that filters the compilation errors and puts them in a format suitable for \SpecialCharNoPassThru LyX reading it. \end_layout \begin_layout Standard In this document we present a filter that recognizes compilation error messages from noweb, gnu C, and the IBM C compiler (xlc). \end_layout \begin_layout Standard The filter is required to read from standard input, parse for error messages and copy the error messages to the standard output. During the output process, the filter must present the error messages in a format that \SpecialCharNoPassThru LyX can interpret, currently, the \SpecialCharNoPassThru LaTeX error message format. Of course, nothing will prevent future \SpecialCharNoPassThru LyX releases from being able to read other formats as well (like gcc error messages for example). This mechanism is necessary to fully explore the literate programming tool's capabilities. \end_layout \begin_layout Section Algorithm \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function bodies \end_layout \end_inset int \end_layout \begin_layout Plain Layout main (int argc, char **argv) \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout if (argc == 2) { \end_layout \begin_layout Plain Layout switch (argv[1][0]) { \end_layout \begin_layout Plain Layout case 'n': \end_layout \begin_layout Plain Layout <<Scan input for noweb error messages>> \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout case 'x': \end_layout \begin_layout Plain Layout <<Scan input for xlc error messages>> \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout case 'a': \end_layout \begin_layout Plain Layout <<AIX system using both noweb and xlc>> \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout case 's': \end_layout \begin_layout Plain Layout case 'b': \end_layout \begin_layout Plain Layout <<Solaris and Linux systems using both noweb and gcc>> \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout case 'g': \end_layout \begin_layout Plain Layout default: \end_layout \begin_layout Plain Layout <<Scan input for gcc error messages>> \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } else { \end_layout \begin_layout Plain Layout <<Scan input for gcc error messages>> \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function prototypes \end_layout \end_inset int main (int argc, char **argv); \end_layout \end_inset \end_layout \begin_layout Section Data Structures \end_layout \begin_layout Standard We resort to some global variables to allow access from several different routines. These are the buffer and related pointers used during the parse of the input. \end_layout \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout <<Global variables>>= \end_layout \begin_layout Plain Layout char buffer[200][200]; \end_layout \begin_layout Plain Layout int last_buf_line; \end_layout \begin_layout Plain Layout int last_err_line; \end_layout \begin_layout Plain Layout int err_line;@ \end_layout \end_inset \end_layout \begin_layout Section The output format \end_layout \begin_layout Standard The output format mimics the \SpecialCharNoPassThru TeX error messages format. This function prints a number of lines residing in the global variable \family typewriter buffer \family default , a program name and line number. There is no special requirement on the input strings, they can be anything. \begin_inset Foot status collapsed \begin_layout Plain Layout This function has been slightly changed from EW's original to make scanning a bit easier with \SpecialCharNoPassThru LaTeX ::scanLogFile(). The test has been added because \SpecialCharNoPassThru LyX can crash if empty lines are allowed here \threehyphens I can't figure out why! \threehyphens BMH \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function bodies \end_layout \end_inset void \end_layout \begin_layout Plain Layout output_error (int buf_size, int error_line, char *tool) \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout int i; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout fprintf(stdout, "! Build Error: ==> %s ==> \backslash n", tool); \end_layout \begin_layout Plain Layout fprintf(stdout, " ... \backslash n \backslash nl.%d ... \backslash n", error_line); \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout for (i=0; i<buf_size; i++) \end_layout \begin_layout Plain Layout if (strlen(buffer[i]) != 0) \end_layout \begin_layout Plain Layout fprintf(stdout, "%s", buffer[i]); \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout fprintf(stdout, " \backslash n"); \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function prototypes \end_layout \end_inset void output_error (int buf_size, int error_line, char *tool); \end_layout \end_inset \end_layout \begin_layout Section Functions Implementation \end_layout \begin_layout Standard Both noweave and notangle routines, always output one single line for each error found, thus to scan the buffer for noweb error messages is enough to exam one input line at a time. Note that the noweb software does not provide a line error number, so all errors boxes related to noweb messages will be displayed at the beginning of the file. \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Scan input for noweb error messages \end_layout \end_inset { \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout while (fgets(buffer[0], 200, stdin)) { \end_layout \begin_layout Plain Layout if (noweb_try(0)) \end_layout \begin_layout Plain Layout output_error(1, err_line, "noweb"); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard The examination itself is very inefficient. Unfortunately noweb doesn't have any characteristic that would help to identify one of its error messages. The solution is to collect all possible output messages in an array of strings, and turn the examination process into a linear search in this array. \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \end_layout \begin_layout Plain Layout <<Global variables>>= \end_layout \begin_layout Plain Layout char *noweb_msgs[] = { \end_layout \begin_layout Plain Layout "couldn't open file", \end_layout \begin_layout Plain Layout "couldn't open temporary file", \end_layout \begin_layout Plain Layout "error writing temporary file", \end_layout \begin_layout Plain Layout "ill-formed option", \end_layout \begin_layout Plain Layout "unknown option", \end_layout \begin_layout Plain Layout "Bad format sequence", \end_layout \begin_layout Plain Layout "Can't open output file", \end_layout \begin_layout Plain Layout "Can't open temporary file", \end_layout \begin_layout Plain Layout "Capacity exceeded:", \end_layout \begin_layout Plain Layout "Ignoring unknown option -", \end_layout \begin_layout Plain Layout "This can't happen:", \end_layout \begin_layout Plain Layout "non-numeric line number in" \end_layout \begin_layout Plain Layout }; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout char *noweb_msgs_mimic_gcc[] = { \end_layout \begin_layout Plain Layout ": unescaped << in documentation chunk" \end_layout \begin_layout Plain Layout }; \end_layout \end_inset \end_layout \begin_layout Standard A noweb error message can be any string that contains a matching pair of < < \begin_inset space ~ \end_inset \begin_inset space ~ \end_inset \begin_inset space ~ \end_inset > >, or any of the above strings \end_layout \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout <<Function bodies>>= \end_layout \begin_layout Plain Layout int noweb_try (int buf_line) \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout char *s, *t, *b; \end_layout \begin_layout Plain Layout int i; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout b = buffer[buf_line]; \end_layout \begin_layout Plain Layout err_line = 0; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout for (i=0; i<1; i++) { \end_layout \begin_layout Plain Layout s = (char *)strstr (b, noweb_msgs_mimic_gcc[i]); \end_layout \begin_layout Plain Layout if (s != NULL) { \end_layout \begin_layout Plain Layout t = (char *)strchr(buffer[buf_line], ':'); \end_layout \begin_layout Plain Layout err_line = atoi(t+1); \end_layout \begin_layout Plain Layout t = buffer[buf_line]; \end_layout \begin_layout Plain Layout ++s; \end_layout \begin_layout Plain Layout while (*(t++) = *(s++)); \end_layout \begin_layout Plain Layout return 1; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout s = (char *)strstr(b, "<<"); \end_layout \begin_layout Plain Layout if (s != NULL) { \end_layout \begin_layout Plain Layout s = (char *)strstr(s+2, ">>"); \end_layout \begin_layout Plain Layout if (s != NULL) { \end_layout \begin_layout Plain Layout return 1; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } else { \end_layout \begin_layout Plain Layout for (i = 0; i < 12; ++i) { \end_layout \begin_layout Plain Layout s = (char *)strstr (b, noweb_msgs[i]); \end_layout \begin_layout Plain Layout if (s != NULL) { \end_layout \begin_layout Plain Layout return 1; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout return 0; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout @ \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout <<Function prototypes>>= \end_layout \begin_layout Plain Layout int noweb_try (int buf_line); \end_layout \begin_layout Plain Layout @ \end_layout \end_inset \end_layout \begin_layout Standard The xlc compiler always outputs one single line for each error found, thus to scan the buffer for xlc error messages it is enough to exam one input line at a time. \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Scan input for xlc error messages \end_layout \end_inset { \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Plain Layout if (xlc_try(0)) \end_layout \begin_layout Plain Layout output_error(1, err_line, "xlc"); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard A xlc error message is easy to identify. Every error message starts with a quoted string with no spaces, a comma, a space, the word \begin_inset Quotes eld \end_inset line \begin_inset Quotes erd \end_inset , a space, and some variable text. The following routine tests if a given buffer line matches this criteria: \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout <<Function bodies>>= \end_layout \begin_layout Plain Layout int \end_layout \begin_layout Plain Layout xlc_try (int buf_line) \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout char *s, *t; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout t = buffer[buf_line]; \end_layout \begin_layout Plain Layout s = t+1; \end_layout \begin_layout Plain Layout while (*s != '"' && *s != ' ' && *s != ' \backslash 0') \end_layout \begin_layout Plain Layout s++; \end_layout \begin_layout Plain Layout if (*t != '"' || *s != '"' || strncmp(s+1, ", line ", 7) != 0) \end_layout \begin_layout Plain Layout return 0; \end_layout \begin_layout Plain Layout s += 8; \end_layout \begin_layout Plain Layout err_line = atoi(s); \end_layout \begin_layout Plain Layout return 1; \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function prototypes \end_layout \end_inset int xlc_try (int buf_line); \end_layout \end_inset \end_layout \begin_layout Standard The gcc compiler error messages are more complicated to scan. Each error can span more than one line in the buffer. The good news is that every buffer line on each error has the same pattern, and share the same line number. Thus the strategy will be to accumulate lines in the buffer while the reported line number is still the same. At the time they differ, all the accumulated lines, except the last one, will belong to one single error message, which now can be output-ed to \SpecialCharNoPassThru LyX . \end_layout \begin_layout Standard Every gcc error message contains a string with no space followed by a \begin_inset Quotes eld \end_inset : \begin_inset Quotes eld \end_inset . If the next character is a space, then this line is a header of a error message and the next line will detail the line number of the source code where the error was found. Otherwise, the next thing is a integer number followed by another \begin_inset Quotes eld \end_inset : \begin_inset Quotes eld \end_inset . \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Scan input for gcc error messages \end_layout \end_inset { \end_layout \begin_layout Plain Layout char *s, *t; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Plain Layout /****** Skip lines until I find an error */ \end_layout \begin_layout Plain Layout s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Plain Layout if (s == NULL || *s == ' ') \end_layout \begin_layout Plain Layout continue; /* No gcc error found here */ \end_layout \begin_layout Plain Layout do { \end_layout \begin_layout Plain Layout <<gcc error message criteria is to find a "...:999:" or a "...: ">> \end_layout \begin_layout Plain Layout /****** OK It is an error message, get line number */ \end_layout \begin_layout Plain Layout err_line = atoi(s+1); \end_layout \begin_layout Plain Layout if (last_err_line == 0 || last_err_line == err_line) { \end_layout \begin_layout Plain Layout last_err_line = err_line; \end_layout \begin_layout Plain Layout continue; /* It's either a header or a continuation, don't output yet */ \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout /****** Completed the scan of one error message, output it to \SpecialCharNoPassThru LyX */ \end_layout \begin_layout Plain Layout discharge_buffer(1); \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout } while (fgets(buffer[last_buf_line], 200, stdin)); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout /****** EOF completes the scan of whatever was being scanned */ \end_layout \begin_layout Plain Layout discharge_buffer(0); \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout gcc error message criteria is to find a "...:999:" or a "...: " \end_layout \end_inset /****** Search first ":" in the error number */ \end_layout \begin_layout Plain Layout s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Plain Layout last_buf_line++; \end_layout \begin_layout Plain Layout if (s == NULL || *s == ' ') \end_layout \begin_layout Plain Layout <<No gcc error found here, but it might terminate the scanning of a previous one>> \end_layout \begin_layout Plain Layout /****** Search second ":" in the error number */ \end_layout \begin_layout Plain Layout t = (char *)strpbrk(s+1, " :");if (t == NULL || *t == ' ') <<No gcc error found here, but it might terminate the scanning of a previous one>>/****** Verify if is all digits between ":" */if (t != s+1+strspn(s+1, "0123456789")) <<No gcc error found here, but it might terminate the scanning of a previous one>>@ \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout <<No gcc error found here, but it might terminate the scanning of a previous one>>= \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout err_line = 0; \end_layout \begin_layout Plain Layout discharge_buffer(1); \end_layout \begin_layout Plain Layout continue; \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard As we mentioned, when the scan of one gcc error message is completed everything in the buffer except the last line is one single error message. But if the scan terminates with a EOF or through finding one line that does not match the gcc error message criteria, then there is no \begin_inset Quotes eld \end_inset last line \begin_inset Quotes erd \end_inset in the buffer to be concerned with. In those cases we empty the buffer completely. \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout <<Function bodies>>= \end_layout \begin_layout Plain Layout void \end_layout \begin_layout Plain Layout discharge_buffer (int save_last) \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout if (last_err_line != 0) { \end_layout \begin_layout Plain Layout clean_gcc_messages(); \end_layout \begin_layout Plain Layout if (save_last != 0) { \end_layout \begin_layout Plain Layout output_error(last_buf_line-1, last_err_line, "gcc"); \end_layout \begin_layout Plain Layout strcpy (buffer[0], buffer[last_buf_line-1]); \end_layout \begin_layout Plain Layout last_err_line = err_line; \end_layout \begin_layout Plain Layout last_buf_line = 1; \end_layout \begin_layout Plain Layout } else { \end_layout \begin_layout Plain Layout ++last_buf_line; \end_layout \begin_layout Plain Layout clean_gcc_messages(); \end_layout \begin_layout Plain Layout output_error(last_buf_line-1, last_err_line, "gcc"); \end_layout \begin_layout Plain Layout last_err_line = 0; \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function prototypes \end_layout \end_inset void discharge_buffer (int save_last); \end_layout \end_inset \end_layout \begin_layout Standard The next function \begin_inset Quotes eld \end_inset cleans \begin_inset Quotes erd \end_inset superfluous information from gcc messages, namely the name of the noweb file and the line number of the Error. \begin_inset Foot status collapsed \begin_layout Plain Layout More could be done. For instance, some way of distinguishing between gcc Errors and Warnings should be devised. \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function bodies \end_layout \end_inset void \end_layout \begin_layout Plain Layout clean_gcc_messages () \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout int index; \end_layout \begin_layout Plain Layout char search [30]; \end_layout \begin_layout Plain Layout char *tail, *head; \end_layout \begin_layout Plain Layout int search_len = sprintf(search, ".nw:%d:", last_err_line); \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout for (index = 0; index < last_buf_line-1; index++) { \end_layout \begin_layout Plain Layout tail = (char *)strstr (buffer[index], search); \end_layout \begin_layout Plain Layout if ( tail == NULL) { \end_layout \begin_layout Plain Layout tail = (char *) strstr (buffer[index], ".nw:"); \end_layout \begin_layout Plain Layout if (tail) { \end_layout \begin_layout Plain Layout tail += 4; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } else { \end_layout \begin_layout Plain Layout tail += search_len; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout if (tail != NULL) { \end_layout \begin_layout Plain Layout head = buffer[index]; \end_layout \begin_layout Plain Layout while (*(head++) = *(tail++)); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Function prototypes \end_layout \end_inset void clean_gcc_messages (); \end_layout \end_inset \end_layout \begin_layout Standard To combine the scan of noweb error messages and xlc error messages is very simple. We just try each one for every input line: \end_layout \begin_layout Standard \begin_inset ERT status open \begin_layout Plain Layout <<AIX system using both noweb and xlc>>= \end_layout \begin_layout Plain Layout { \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout while (fgets(buffer[0], 200, stdin)) { \end_layout \begin_layout Plain Layout if (noweb_try(0)) \end_layout \begin_layout Plain Layout output_error(1, err_line, "noweb"); \end_layout \begin_layout Plain Layout else if (xlc_try(0)) \end_layout \begin_layout Plain Layout output_error(1, err_line, "xlc"); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout @ \end_layout \end_inset \end_layout \begin_layout Standard To combine the scan of noweb error messages and gcc error messages is simple if we realize that it is not possible to find a noweb error message in the middle of a gcc error message. So we just repeat the gcc procedure and test for noweb error messages in the beginning of the scan: \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout Solaris and Linux systems using both noweb and gcc \end_layout \end_inset { \end_layout \begin_layout Plain Layout char *s, *t; \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout last_buf_line = 0; \end_layout \begin_layout Plain Layout while (fgets(buffer[last_buf_line], 200, stdin)) { \end_layout \begin_layout Plain Layout /****** Skip lines until I find an error */ \end_layout \begin_layout Plain Layout if (last_buf_line == 0 && noweb_try(0)) { \end_layout \begin_layout Plain Layout output_error(1, err_line, "noweb"); \end_layout \begin_layout Plain Layout continue; \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout s = (char *)strpbrk(buffer[last_buf_line], " :"); \end_layout \begin_layout Plain Layout if (s == NULL || *s == ' ') \end_layout \begin_layout Plain Layout continue; /* No gcc error found here */ \end_layout \begin_layout Plain Layout do { \end_layout \begin_layout Plain Layout <<gcc error message criteria is to find a "...:999:" or a "...: ">> \end_layout \begin_layout Plain Layout /****** OK It is an error, get line number */ \end_layout \begin_layout Plain Layout err_line = atoi(s+1); \end_layout \begin_layout Plain Layout if (last_err_line == 0 || last_err_line == err_line) { \end_layout \begin_layout Plain Layout last_err_line = err_line; \end_layout \begin_layout Plain Layout continue; /* It's either a header or a continuation, don't output yet */ \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout /****** Completed the scan of one error message, output it to \SpecialCharNoPassThru LyX */ \end_layout \begin_layout Plain Layout discharge_buffer(1); \end_layout \begin_layout Plain Layout break; \end_layout \begin_layout Plain Layout } while (fgets(buffer[last_buf_line], 200, stdin)); \end_layout \begin_layout Plain Layout } \end_layout \begin_layout Plain Layout /****** EOF completes the scan of whatever was being scanned */ \end_layout \begin_layout Plain Layout discharge_buffer(0); \end_layout \begin_layout Plain Layout } \end_layout \end_inset \end_layout \begin_layout Section Wrapping the code into a file \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout listerrors.c \end_layout \end_inset #include <stdio.h> \end_layout \begin_layout Plain Layout #include <strings.h> \end_layout \begin_layout Plain Layout \end_layout \begin_layout Plain Layout <<Global variables>> \end_layout \begin_layout Plain Layout <<Function prototypes>> \end_layout \begin_layout Plain Layout <<Function bodies>> \end_layout \end_inset \end_layout \begin_layout Standard To build this program, we want to add the \begin_inset Quotes eld \end_inset -L \begin_inset Quotes erd \end_inset option in the tangle command to force gdb to load the file \family typewriter Literate.nw \family default instead of \family typewriter listerrors.c \family default . In accordance with this, we pass the \begin_inset Quotes eld \end_inset -g \begin_inset Quotes erd \end_inset option to gcc. \end_layout \begin_layout Standard \begin_inset Flex Chunk status open \begin_layout Plain Layout \begin_inset Argument 1 status open \begin_layout Plain Layout build-script \end_layout \end_inset #!/bin/sh \end_layout \begin_layout Plain Layout if [ -z "$NOWEB_SOURCE" ]; then NOWEB_SOURCE=Literate.nw; fi \end_layout \begin_layout Plain Layout if [ -z "$NOWEB_OUTPUT_DIR" ]; then NOWEB_OUTPUT_DIR=.; fi \end_layout \begin_layout Plain Layout notangle -L -Rlisterrors.c ${NOWEB_SOURCE} > ${NOWEB_OUTPUT_DIR}/listerrors.c \end_layout \begin_layout Plain Layout gcc -g -o listerrors listerrors.c \end_layout \end_inset \end_layout \begin_layout Standard This project can be tangled and compiled from \SpecialCharNoPassThru LyX if you set \family typewriter \backslash build_command \family default to call a generic script that always extracts a chunk named \family typewriter build-script \family default and executes it. Here is a example of such generic script: \end_layout \begin_layout LyX-Code #!/bin/sh \begin_inset Newline newline \end_inset notangle -Rbuild-script $1 | env NOWEB_SOURCE=$1 NOWEB_OUTPUT_DIR=$r sh \end_layout \begin_layout LyX-Code \end_layout \end_body \end_document