1%D \module 2%D [ file=file-mod, % was supp-fil, 3%D version=20110701, % 1995.10.10, 4%D title=\CONTEXT\ File Macros, 5%D subtitle=Resolvers, 6%D author=Hans Hagen, 7%D date=\currentdate, 8%D copyright={PRAGMA ADE \& \CONTEXT\ Development Team}] 9%C 10%C This module is part of the \CONTEXT\ macro||package and is 11%C therefore copyrighted by \PRAGMA. See mreadme.pdf for 12%C details. 13 14%D We could move some more to the lua end (implementors). 15 16\writestatus{loading}{ConTeXt File Macros / Resolvers} 17 18\unprotect 19 20\registerctxluafile{file-res}{} 21 22%D \macros 23%D {readfile,ReadFile} 24%D 25%D One cannot be sure if a file exists. When no file can be found, the \type 26%D {\input} primitive gives an error message and switches to interactive mode. The 27%D macro \type {\readfile} takes care of non||existing files. This macro has two 28%D faces. 29%D 30%D \starttyping 31%D \ReadFile {filename} 32%D \readfile {filename} {before loading} {not found} 33%D \stoptyping 34%D 35%D Many \TEX\ implementations have laid out some strategy for locating files. This 36%D can lead to unexpected results, especially when one loads files that are not 37%D found in the current directory. Let's give an example of this. In \CONTEXT\ 38%D illustrations can be defined in an external file. The resizing macro first looks 39%D if an illustration is defined in the local definitions file. When no such file is 40%D found, it searches for a global file and when this file is not found either, the 41%D illustration itself is scanned for dimensions. One can imagine what happens if an 42%D adapted, localy stored illustration, is scaled according to dimensions stored 43%D somewhere else. 44%D 45%D When some \TEX\ implementation starts looking for a file, it normally first looks 46%D in the current directory. When no file is found, \TEX\ starts searching on the 47%D path where format and|/|or style files are stored. Depending on the 48%D implementation this can considerably slow down processing speed. 49%D 50%D In \CONTEXT, we support a project||wise ordening of files. In such an approach it 51%D seems feasible to store common files in a lower directory. When for instance 52%D searching for a general layout file, we therefore have to backtrack. 53%D 54%D These three considerations have lead to a more advanced approach for loading 55%D files. 56%D 57%D We first present an earlier implementation of \type {\readfile}. This command 58%D backtracks parent directories, upto a predefined level. Users can change this 59%D level (on the commandline using a directive); we default to~3. 60%D 61%D We use \type {\normalinput} instead of \type {\input} because we want to be able 62%D to redefine the original \type {\input} when needed, for instance when loading 63%D third party libraries. 64 65\mutable\lettonothing\readfilename 66 67\def\syst_files_read_file#protocol#path#name% #true #false 68 {\edef\readfilename{{#protocol}{#path}{#name}}% 69 \ifempty\readfilename 70 \expandafter\secondoftwoarguments 71 \else 72 \expandafter\syst_files_read_file_indeed 73 \fi} 74 75\def\syst_files_read_file_indeed#true#false% 76 {#true% 77 \relax 78 \normalinput{\readfilename}% 79 \relax} 80 81%D \macros 82%D {readjobfile,readlocfile,readsysfile, 83%D readfixfile,readsetfile} 84%D 85%D This implementation honnors the third situation, but we still can get unwanted 86%D files loaded and/or can get involved in extensive searching. 87%D 88%D Due to different needs, we decided to offer four alternative loading commands. 89%D With \type {\readjobfile} we load a local file and do no backtracking, while 90%D \type {\readlocfile} backtracks~\number \maxreadlevel\ directories, including the 91%D current one. 92%D 93%D System files can be anywhere and therefore \type {\readsysfile} is not bound to 94%D the current directory and obeys the \TEX\ implementation. 95%D 96%D Of the last two, \type {\readfixfile} searches on the directory specified and 97%D backtracks too, while \type {\readsetfile} does only search on the specified 98%D path. 99%D 100%D The most liberal is \type {\readfile}. 101 102\permanent\protected\def\readjobfile #name{\syst_files_read_file{job} {.}{#name}} % current path, no backtracking 103\permanent\protected\def\readlocfile #name{\syst_files_read_file{loc} {.}{#name}} % current path, backtracking 104\permanent\protected\def\readsysfile #name{\syst_files_read_file{sys} {.}{#name}} % current path, obeys tex search 105\permanent\protected\def\readfixfile#path#name{\syst_files_read_file{fix}{#path}{#name}} % specified path, backtracking 106\permanent\protected\def\readsetfile#path#name{\syst_files_read_file{set}{#path}{#name}} % specified path, no backtracking 107\permanent\protected\def\readfile #name{\syst_files_read_file{any} {.}{#name}} 108\permanent\protected\def\ReadFile #name{\syst_files_read_file{any} {.}{#name}\donothing\donothing} 109 110%D So now we've got ourselves five file loading commands: 111%D 112%D \starttyping 113%D \readfile {filename} {before loading} {not found} 114%D 115%D \readjobfile {filename} {before loading} {not found} 116%D \readlocfile {filename} {before loading} {not found} 117%D \readfixfile {filename} {before loading} {not found} 118%D \readsysfile {directory} {filename} {before loading} {not found} 119%D \stoptyping 120 121\permanent\protected\def\readtexfile#name#true#false% 122 {\pushcatcodetable 123 \catcodetable\ctxcatcodes 124 \readfile{#name}{#true}{#false}% 125 \popcatcodetable} 126 127% \permanent\protected\def\readxmlfile#name#true#false% 128% {\pushcatcodetable 129% \catcodetable\xmlcatcodes 130% \readfile{#name}{#true}{#false}% 131% \popcatcodetable} 132 133%D \macros 134%D {doiflocfileelse,locfilename} 135%D 136%D \starttyping 137%D \doiflocfileelse {filename} {before loading} {not found} 138%D \stoptyping 139 140\permanent\protected\def\doifelselocfile#name{{#name}} 141\permanent \def\locfilename #name{ {#name}} 142 143\aliased\let\doiflocfileelse\doifelselocfile 144 145\protect \endinput 146 |
