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\writestatus{loading}{ConTeXt File Macros / Resolvers} 15 16\unprotect 17 18\registerctxluafile{file-res}{} 19 20%D \macros 21%D {readfile,ReadFile} 22%D 23%D One cannot be sure if a file exists. When no file can be 24%D found, the \type{\input} primitive gives an error message 25%D and switches to interactive mode. The macro \type{\readfile} 26%D takes care of non||existing files. This macro has two faces. 27%D 28%D \starttyping 29%D \ReadFile {filename} 30%D \readfile {filename} {before loading} {not found} 31%D \stoptyping 32%D 33%D Many \TEX\ implementations have laid out some strategy for 34%D locating files. This can lead to unexpected results, 35%D especially when one loads files that are not found in the 36%D current directory. Let's give an example of this. In 37%D \CONTEXT\ illustrations can be defined in an external file. 38%D The resizing macro first looks if an illustration is defined 39%D in the local definitions file. When no such file is found, 40%D it searches for a global file and when this file is not 41%D found either, the illustration itself is scanned for 42%D dimensions. One can imagine what happens if an adapted, 43%D localy stored illustration, is scaled according to 44%D dimensions stored somewhere else. 45%D 46%D When some \TEX\ implementation starts looking for a file, it 47%D normally first looks in the current directory. When no file 48%D is found, \TEX\ starts searching on the path where format 49%D and|/|or style files are stored. Depending on the implementation 50%D this can considerably slow down processing speed. 51%D 52%D In \CONTEXT, we support a project||wise ordening of files. 53%D In such an approach it seems feasible to store common files 54%D in a lower directory. When for instance searching for a 55%D general layout file, we therefore have to backtrack. 56%D 57%D These three considerations have lead to a more advanced 58%D approach for loading files. 59%D 60%D We first present an earlier implementation of 61%D \type{\readfile}. This command backtracks parent 62%D directories, upto a predefined level. Users can change this 63%D level (on the commandline using a directive); we default to~3. 64%D 65%D We use \type{\normalinput} instead of \type{\input} 66%D because we want to be able to redefine the original 67%D \type{\input} when needed, for instance when loading third 68%D party libraries. 69 70\let\readfilename\empty 71 72\def\syst_files_read_file#protocol#path#name% #true #false 73 {\edef\readfilename{{#protocol}{#path}{#name}}% 74 \ifx\readfilename\empty 75 \expandafter\secondoftwoarguments 76 \else 77 \expandafter\syst_files_read_file_indeed 78 \fi} 79 80\def\syst_files_read_file_indeed#true#false% 81 {#true% 82 \relax 83 \normalinput{\readfilename}% 84 \relax} 85 86%D \macros 87%D {readjobfile,readlocfile,readsysfile, 88%D readfixfile,readsetfile} 89%D 90%D This implementation honnors the third situation, but we 91%D still can get unwanted files loaded and/or can get involved 92%D in extensive searching. 93%D 94%D Due to different needs, we decided to offer four alternative 95%D loading commands. With \type{\readjobfile} we load a local 96%D file and do no backtracking, while \type{\readlocfile} 97%D backtracks~\number\maxreadlevel\ directories, including the current 98%D one. 99%D 100%D System files can be anywhere and therefore 101%D \type{\readsysfile} is not bound to the current directory 102%D and obeys the \TEX\ implementation. 103%D 104%D Of the last two, \type{\readfixfile} searches on the 105%D directory specified and backtracks too, while 106%D \type{\readsetfile} does only search on the specified path. 107%D 108%D The most liberal is \type {\readfile}. 109 110\unexpanded\def\readjobfile #name{\syst_files_read_file{job} {.}{#name}} % current path, no backtracking 111\unexpanded\def\readlocfile #name{\syst_files_read_file{loc} {.}{#name}} % current path, backtracking 112\unexpanded\def\readsysfile #name{\syst_files_read_file{sys} {.}{#name}} % current path, obeys tex search 113\unexpanded\def\readfixfile#path#name{\syst_files_read_file{fix}{#path}{#name}} % specified path, backtracking 114\unexpanded\def\readsetfile#path#name{\syst_files_read_file{set}{#path}{#name}} % specified path, no backtracking 115\unexpanded\def\readfile #name{\syst_files_read_file{any} {.}{#name}} 116\unexpanded\def\ReadFile #name{\syst_files_read_file{any} {.}{#name}\donothing\donothing} 117 118%D So now we've got ourselves five file loading commands: 119%D 120%D \starttyping 121%D \readfile {filename} {before loading} {not found} 122%D 123%D \readjobfile {filename} {before loading} {not found} 124%D \readlocfile {filename} {before loading} {not found} 125%D \readfixfile {filename} {before loading} {not found} 126%D \readsysfile {directory} {filename} {before loading} {not found} 127%D \stoptyping 128 129\unexpanded\def\readtexfile#name#true#false% 130 {\pushcatcodetable 131 \catcodetable\ctxcatcodes 132 \readfile{#name}{#true}{#false}% 133 \popcatcodetable} 134 135\unexpanded\def#name#true#false% 136 {\pushcatcodetable 137 \catcodetable\xmlcatcodes 138 \readfile{#name}{#true}{#false}% 139 \popcatcodetable} 140 141%D \macros 142%D {doiflocfileelse,locfilename} 143%D 144%D \starttyping 145%D \doiflocfileelse {filename} {before loading} {not found} 146%D \stoptyping 147 148\unexpanded\def\doifelselocfile#name{{#name}} 149 \def\locfilename #name{ {#name}} 150 151\let\doiflocfileelse\doifelselocfile 152 153\protect \endinput 154 |
