#* pars/compile.pss This is a parse-script which compiles parse-scripts (!). What is more, it can compile itself... so we can do >> pep -f compile.pss compile.pss > asm.new.pp This is useful because the resulting 'assembler' program (in sav.pp) and printed to stdout, can be used as a replacement for 'asm.pp' which is the default parse-script language compiler. The advantage is that it is easier to maintain and add new sytax to compile.pss than it is to 'asm.pp'. This script uses the virtual machine and engine implemented at http://bumble.sf.net/books/pars/object/ It implements a script language with a syntax reminiscent of sed and awk (much simpler than awk, but more complex than sed). This code was created in a straightforward manner by adapting the "assembled" code in 'asm.pp'. Some extra error checks were added. Also, the EOF test was placed at the end of the script to remove the 'last character' bug. It was evident that using the script language is much more comfortable that hand-coding parse machine assembler programs. HOW TO ADD A NEW COMMAND TO PEP In general, we would like to avoid adding new commands (instructions) to the pep script-language/machine since we would like to keep the machine and language as simple as possible. However, after great thought and cogitation, sometimes new commands or features seem like a good idea. To add a new command the process is as follows: Add a constant in command.h and command.c in the info[] array. Implement the commmand in machine.interp.c in the big switch statement. Then modify compile.pss to recognise the command when it is in a script. Then copy asm.pp to asm.old.pp Then do >> pep -f compile.pss compile.pss > asm.new.pp >> cp asm.new.pp asm.pp Now test your "newcommand" with eg >> pep -e "r; newcommand; t;d;" -i "abcd" Now, if you wish, add the new command to the various translation scripts in the tr/ folder. The modifications required in the translation scripts are very similar to the modifications made to the "compile.pss" script, except that the target language is different. REPLACING ASMPP We can use this script as a replacement for "asm.pp" or "asm.handcode.pp" which is a script assembler written by hand in the parse machine assembly format (1 command per line, labels, jumps, tests, etc). * replace asm.pp with compile.pss ----- # generate the new script assembler cp asm.pp asm.old; pep -f compile.pss compile.pss > asm.new.pp cp asm.new.pp asm.pp # test the new assembler (the script "r;t;t;t;d;" will be compiled # by the new asm.pp which we have just created. pep -e "r;t;t;t;d;" -i "abcd" # output: aaabbbcccddd ,,, The advantage of all this, is that it is much easier to maintain and add new syntax to "pars/compile.pss" than it is directly, to "pars/asm.pp" For example asm.handcode.pp still uses "rabbit hops" to compile "quoteset" tokens (an old version of the "ortestset" token), which is very inefficient but compile.pss uses the new look-ahead technique. Also, there are negated tests implemented in compile.pss but not implemented in asm.handcode.pp I will no longer continue to maintain asm.handcode.pp because its real purpose was to "bootstrap" the current script. I will maintain working copies of asm.pp as generated by this script in case of future errors. NOTES The accumulator register was being used to generate true-jump targets for testsets, but no longer This script can be used as the basis for many others which transform scripts in some way. For example, to 'pretty-print' scripts, or to generate compilable c code for a script using the functions in machine.methods.c. So, instead of compiling to the "assembler" format for the machine (which is then interpreted by the code in pep.c) we can compile to a series of c function calls. This is c source code which can be compiled with gcc, producing an executable version of the target script. This is an interesting idea, because we can transform a script into compilable or executable code in a different language with a different 'Machine' object. So, for example, we could write a Machine object in Ruby or Java or Python or x86 assembler and then generate compilable or executable code for that target environment. The compilable code would consist of a series of method calls for the given object and test and jumps. It will also be interesting to see if there is a significant performance advantage in running executed, rather than interpreted scripts. see tr/translate.c.pss or tr/translate.go.pss for creating executable parse programs from scripts GRAMMAR NOTES The machine cannot directly implement the ebnf structures of repetition "{...}", optionality "[...]" or grouping "(...)", so we need to express all grammar rules only in terms of alternation |. Quotesets are a handy way to express this in a script, eg * bnf rule: alpha ::= a | b | c ; >> 'a','b','c' { clear; add "alpha*"; push; .reparse } It is sometimes straightforward to factor out the above ebnf structures, but the result is a greater number of rules. SEE ALSO At http://bumble.sf.net/books/pars/ object/pep.c the current implementation of the machine interpreter and debugger. object/*.c the virtual machine and components tr/translate.java.pss compiles pep scripts to a stand-alone java source code file tr/translate.go.pss tr/translate.ruby.pss tr/translate.python.pss As above, for go, ruby and python. asm.handcode.pp a handcoded "assembly" compiler of the parse script language for a previous version of the script language. This was how I initially "bootstrapped" the pep language (before using the current file, compile.pss to create new versions of the pep language). USAGE This script is used to replace the hand-coded assembler file "asm.handcode.pp" since it is much easier to maintain and add new syntax for the parse-script language. Comments are preserved (largely) in the output file. We can also do the seemingly strange operation >> pep -f compile.pss compile.pss which actually creates an 'assembler' version of itself in 'sav.pp' which is then be suitable for use as an 'asm.pp' substitute. (This is how we modify the syntax of the pep language, if need be). This is quite tricky to think about since it is so self-referential. This is analogous to the equally strange operation >> pep -f tr/translate.c.pss tr/translate.c.pss > eg/clang/tr.clang.c which generates a compilable c language program of the compilable script. It is possible to compile this script into a stand-alone executable with: ---- pep -f tr/translate.c.pss tr/translate.c.pss > eg/clang/tr.clang.c cd eg/clang/ gcc -o tr.clang.c -Lobject -lmachine -Iobject ,,,, TESTING * view how this script compiles an inline script >> pep -f compile.pss -i "[aeiou] {a '(vowel)'; } t;d;" The result will also be saved in "sav.pp" * see how the compiled script runs >> pep -a sav.pp -i "abcde" output: a(vowel)bcde(vowel) * test "test chaining" compilation >> pep -f compile.pss -i "r;'a','b','c'{t;}t;d;" >> pep -a sav.pp -i "axbxcx" output should be: aaxbbxccx * view/debug how compile.pss compiles test chains (or something else) >> pep -If compile.pss -i "r;'a','b','c'{t;}t;d;" This provides interactive debugging of the compilation process. FIXED BUGS I was getting segmentation faults because of one-off errors etc >> pep -f compile.pss compile.pss Mainly fixed with "valgrind", but still a bug in "until" (in object/machine.interp.c execute()... need to implement endsWith() function. And one other bug. * didnt need 2 jumps after "tests", just 1 jumpfalse or jumptrue used "replace" to remove the unnecessary jump * eg: add "\\"; threw an error and also: replace "\\" "\\\\"; This was a problem with the "until" implementation in machine.interp.c It was actually necessary to count the number of escape chars before the suffix. If even, break, if not, dont. BUGS * missing braces in scripts dont produce good error messages, just a cryptic "script could not be compiled". * should I unescape single quotes in single quote blocks?? eg ' abc\'xyz' will become " abc'xyz" * doesnt catch B[abc] or E[a-z] type errors in scripts. Also doesnt catch "r;r;d" type errors. * Also, un-balanced braces give cryptic error messages compile.pss should not write the compiled script to stdout because then asm.pp will do the same thing. easy enough to fix in asm.pp as well (comment out final 2 "print" commands). Comments may not be parsing correctly. Comments and multiline comments should not jump back to read after deleting the comment, because there could be no more input, and read will throw an error. They should jump to the EOF end-of-file check. Or they could just call ".reparse" which is safe but not very efficient. TODO Add an "echar" command that changes the default escape character. Also, in some languages a character actually escapes itself, eg '' is ' escaped! We could allow single argument "replace" command eg: >> replace "x"; which is equivalent to >> replace "x" "": Need to catch multiline quote errors when used with the "until" command. Separate error checking into a new script, and make pep load an assembled version of this error checker. This will allow the same error checker to be used with the scripts tr/translate.java.pss tr/translate.tcl.pss etc. HISTORY 15 june 2021 Adding the commands "upper" "lower" and "cap" "nochars" "nolines" 13 march 2020 Added compilation for multiline arguments for the "add" command. Appears to be working. 15 sept 2019 Realised that I can have an eof error check block at the end of the script just before all the tokens are pushed back on the stack. See the 1 and 2 token eof error check in this script. 13 september 2019 Adding "mark" and "go" commands here. Improved unterminated quote '/" error messages. In general it is much more helpful to catch the error when it happens and print an informative message (with line-number etc). 5 september 2019 Added a "stack" and "unstack" command to the machine and to compile.pss 29 august 2019 Improved some error checks. Could make the error check code more succinct. Changed the way testeof and testtape are parsed to include them with other tests. This also allows to negate them with !(==) and !(eof) and also to concatenate with other tests eg: (eof),B"abc" {} added extra syntax and <==> for these tests. 25 august 2019 Realised that I dont need 2 jumps for OR test concatenation (with ',') That will greatly improve script interpretation efficiency. Added AND concatenation logic to tests so now we can do * test if workspace begins with 'a' AND ends with 'z' >> B"a".E"z" {} Changed the way .reparse and .restart are parsed and compiled. These are now parsed as 2 tokens ".*word*". This allows me to use '.' for AND logic concatenation in tests. It also allows me to provide special semantic meaning to commands beginning with a dot, which seems like a good thing. Added "delim" command here and in machine.c and machine.interp.c, to change the stack delimiter. 24 august 2019 The "state*" token should be separated into "testeof*" and "testtape*" and then the 2 tests can be elided.(done) The conversion to a "test*{*" rule and ellision of multiple tests will make this script much more compact and hopefully just as readable. Also, as a side effect, negation of all tests will be available soon. Also, it is possible to chain together different types of tests. Converted quoteset to "ortestset*" and "andtestset*". I will introduce a new notation namely: * check if workspace begins with "abc" AND ends with "xyz" >> B"abc" . E"xyz" { commands } so the dot will become an "AND" (&&) concatenator of tests and "," will remain as the "OR" (||) concatenator of tests In these || and && test lists any type of test can be included for example * check if workspace starts with "a", only contains chars a|b|c * and ends with the letter "z" (using "." AND concatenator) >> B"abc" . [abc] . E"z" { ... } Experimenting with the new technique to create negated tokens classes. * test negated tokens for the equality test >> pep -f compile.pss -i 'r;!"b",!"a"{nop;}' 23 august 2019 Adding begintests B"..." { } and endtests E"..." {} to the quoteset logic. But need to juggle the combinations. Also will add classes and negated classes. More or less working. But should actually change parsing to make quotesets more flexible, see the section of the script for details. The new quoteset compilation seems to be working. Needs more testing. We can now use compile.pss as a replacement for asm.pp. Converting to a new quoteset (eg: 'n','m' {...} ) lookahead compiling technique. Also we can compile comments with rules for "comment*command*" and "command*comment*" and "comment*comment*" -> "comment*". Instead of the current shenanigins. 14 august 2019 trying to preserve comments here but cant reduce comments with tokens like {* }* !* etc because we never retrieve the attributes for those tokens. more thought required. Added a !"text" {...} syntax. very simple to add here. did the same in compilable.c.pss Added a "begin" block to this (for start configurations of scripts). Also need to improve the compilation of "quoteset*" tokens which produce nifty but very poor code. need 'tapereplace' command for this? 30 july 2019 Fixed the last character bug by putting the EOF test at the very end of the file. The translation is complete and the script appears to be working but no doubt will contain bugs. Initially translated from asm.pp. *# read; #-------------- [:space:] { clear; .reparse } #--------------- # We can ellide all these single character tests, because # the stack token is just the character itself with a * # Braces {} are used for blocks, ',' and '.' for concatenating # tests with OR or AND logic. 'B' and 'E' for begin and end # tests. "{", "}", ";", ",", ".", "!", "B", "E" { put; add "*"; push; .reparse } #--------------- # format: "text" "\"" { # save the line number in case there is no terminating # quote. clear; ll; put; clear; add '"'; until '"'; !E'"' { clear; add 'Unterminated quote (") starting at line '; get; add ' !\n'; print; quit; } put; clear; add "quote*"; push; .reparse } #--------------- # format: 'text', single quotes are converted to double quotes # but we must escape embedded double quotes. "'" { # save the line number in case there is no terminating # quote. clear; ll; put; clear; until "'"; !E"'" { clear; add "Unterminated quote (') starting at line "; get; add '!\n'; print; quit; } # should we unescape single quotes here?? clip; escape '"'; put; clear; add "\""; get; add "\""; put; clear; add "quote*"; push; .reparse } #--------------- # formats: [:space:] [a-z] [abcd] [:alpha:] etc "[" { until "]"; put; clear; add "class*"; push; .reparse } #--------------- # formats: (eof) (==) etc. I may change this syntax to just # EOF and == "(" { clear; until ")"; clip; put; "eof","EOF" { clear; add "eof*"; push; .reparse } "==" { clear; add "tapetest*"; push; .reparse } add " << unknown test near line "; ll; add " of script.\n"; add " bracket () tests are \n"; add " (eof) test if end of stream reached. \n"; add " (==) test if workspace is same as current tape cell \n"; print; clear; quit; } #--------------- # multiline and single line comments, eg #... and #* ... *# "#" { clear; read; "\n" { clear; .reparse } # checking for multiline comments of the form "#* \n\n\n *#" # these are just ignored at the moment (deleted) "*" { # save the line number for possible error message later clear; ll; put; clear; until "*#"; E"*#" { # convert to # single-line comments clip; clip; #put; clear; add "#*"; get; add "*#"; replace "\n" "\n#"; # create a "comment" parse token put; clear; add "comment*"; push; .reparse } # make an unterminated multiline comment an error # to ease debugging of scripts. clear; add "unterminated multiline comment #* ... *# \n"; add "stating at line number "; get; add "\n"; print; clear; quit; } # single line comments. some will get lost. put; clear; add "#"; get; until "\n"; clip; put; clear; add "comment*"; push; .reparse } #---------------------------------- # parse command words (and abbreviations) # legal characters for keywords (commands) ![abcdefghijklmnopqrstuvwxyzBEKGPRUWS+-<>0^] { # error message about a misplaced character put; clear; add "!! Misplaced character '"; get; add "' in script near line "; ll; add " (character "; cc; add ") \n"; print; clear; bail; } # my testclass implementation cannot handle complex lists # eg [a-z+-] this is why I have to write out the whole alphabet while [abcdefghijklmnopqrstuvwxyzBEOFKGPRUWS+-<>0^]; #---------------------------------- # KEYWORDS # here we can test for all the keywords (command words) and their # abbreviated one letter versions (eg: clip k, clop K etc). Then # we can print an error message and abort if the word is not a # legal keyword for the parse-edit language # make ll an alias for "lines" and cc an alias for chars "lines" { clear; add "ll"; } "chars" { clear; add "cc"; } # one letter command abbreviations "a" { clear; add "add"; } "k" { clear; add "clip"; } "K" { clear; add "clop"; } "D" { clear; add "replace"; } "d" { clear; add "clear"; } "t" { clear; add "print"; } "p" { clear; add "pop"; } "P" { clear; add "push"; } "u" { clear; add "unstack"; } "U" { clear; add "stack"; } "G" { clear; add "put"; } "g" { clear; add "get"; } "x" { clear; add "swap"; } ">" { clear; add "++"; } "<" { clear; add "--"; } "m" { clear; add "mark"; } "M" { clear; add "go"; } "r" { clear; add "read"; } "R" { clear; add "until"; } "w" { clear; add "while"; } "W" { clear; add "whilenot"; } # we can probably omit tests and jumps since they are not # designed to be used in scripts (only assembled parse programs). #* "b" { clear; add "jump"; } "j" { clear; add "jumptrue"; } "J" { clear; add "jumpfalse"; } "=" { clear; add "testis"; } "?" { clear; add "testclass"; } "b" { clear; add "testbegins"; } "B" { clear; add "testends"; } "E" { clear; add "testeof"; } "*" { clear; add "testtape"; } *# "n" { clear; add "count"; } "+" { clear; add "a+"; } "-" { clear; add "a-"; } "0" { clear; add "zero"; } "c" { clear; add "cc"; } "chars" { clear; add "cc"; } "l" { clear; add "ll"; } "lines" { clear; add "ll"; } "^" { clear; add "escape"; } "v" { clear; add "unescape"; } "z" { clear; add "delim"; } "S" { clear; add "state"; } "q" { clear; add "quit"; } "Q" { clear; add "bail"; } "s" { clear; add "write"; } "o" { clear; add "nop"; } "rs" { clear; add "restart"; } "rp" { clear; add "reparse"; } # some extra syntax for testeof and testtape "","" { put; clear; add "eof*"; push; .reparse } "<==>" { put; clear; add "tapetest*"; push; .reparse } #* "nochars", "nolines" { put; clear; add "The command '"; get; add "' (near line "; ll; add ")\n"; add "has not been implemented, but needs to be. \n"; print; clear; quit; } *# "add","clip","clop","replace","clear", "upper","lower","cap","print", "pop","push","unstack","stack","put","get","swap", "++","--","mark","go", "read","until","while","whilenot", "jump","jumptrue","jumpfalse", "testis","testclass","testbegins","testends", "testeof","testtape", "count","a+","a-","zero","cc","ll", "nochars","nolines", "escape","unescape","delim","state","quit","bail", "write","nop","reparse","restart" { put; clear; add "word*"; push; .reparse } #------------ # the .reparse command and "parse label" is a simple way to # make sure that all shift-reductions occur. It should be used inside # a block test, so as not to create an infinite loop. "parse>" { clear; add "parse:"; put; clear; add "command*"; push; .reparse } # -------------------- # try to implement begin-blocks, which are only executed # once, at the beginning of the script (similar to awk's BEGIN {} rules) "begin" { put; add "*"; push; .reparse } put; add "Pep syntax error: unknown command '"; get; add "' \n"; add "on line "; ll; add " (or character "; cc; add ")"; add "of input (file or stream). \n"; print; clear; quit; # ---------------------------------- # PARSING PHASE: # the lexing phase finishes here, and below is the # parse/compile phase of the script. Here we pop tokens # off the stack and check for sequences of tokens eg word*semicolon* # If we find a valid series of tokens, we "shift-reduce" or "resolve" # the token series eg word*semicolon* --> command* # # At the same time, we manipulate (transform) the attributes on the # tape, as required. So Tape=|pop|;| becomes |\npop| where the # bars | indicate tape cells. (2 tapes cells are merged into 1). # # Each time the stack is reduced, the tape must also be reduced # parse> #------------------------------------- # 2 tokens #------------------------------------- pop; pop; # All of the below are currently errors, but may not # be in the future if we expand the syntax of the parse # language. Also consider: # begintext* endtext* quoteset* notclass*, !* ,* ;* B* E* # It is nice to trap the errors here because we can emit some # hopefully not-very-cryptic error messages with a line number. # Otherwise the script writer has to debug with # pep -a asm.pp scriptfile -I # "word*word*", "word*}*", "word*begintext*", "word*endtext*", "word*!*", "word*,*", "quote*word*", "quote*class*", "quote*state*", "quote*}*", "quote*begintext*", "quote*endtext*", "class*word*", "class*quote*", "class*class*", "class*state*", "class*}*", "class*begintext*", "class*endtext*", "class*!*", "notclass*word*", "notclass*quote*", "notclass*class*", "notclass*state*", "notclass*}*" { push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script (missing semicolon/brace/unescaped quote??) \n"; print; clear; quit; } "{*;*", ";*;*", "}*;*" { push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script: misplaced semi-colon? ; \n"; print; clear; quit; } # comma errors. ",*;*", ",*{*", ",*}*" { push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script: misplaced comma? ; \n"; print; clear; quit; } ",*{*" { push; push; add "Pep: error near line "; ll; add " (char "; cc; add ")"; add " of script: extra comma in list? \n"; print; clear; quit; } "command*;*","commandset*;*" { push; push; add "Pep: error near line "; ll; add " (char "; cc; add ")"; add " of script: extra semi-colon? \n"; print; clear; quit; } "!*!*" { push; push; add "Pep: error near line "; ll; add " (char "; cc; add ")"; add " of script: \n double negation '!!' is not implemented \n"; add " and probably won't be, because what would be the point? \n"; print; clear; quit; } "!*{*","!*;*" { push; push; add "Pep: error near line "; ll; add " (char "; cc; add ")"; add " of script: misplaced negation operator (!)? \n"; add " The negation operator precedes tests, for example: \n"; add " !B'abc'{ ... } or !(eof),!'abc'{ ... } \n"; print; clear; quit; } ",*command*" { push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script: misplaced comma? \n"; print; clear; quit; } "!*command*" { push; push; add "error near line "; ll; add " (at char "; cc; add ") \n"; add " The negation operator (!) cannot precede a command \n"; print; clear; quit; } ";*{*", "command*{*", "commandset*{*" { push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script: no test for brace block? \n"; print; clear; quit; } "{*}*" { push; push; add "error near line "; ll; add " of script: empty braces {}. \n"; print; clear; quit; } "B*class*","E*class*" { push; push; add "error near line "; ll; add " of script:\n classes ([a-z], [:space:] etc). \n"; add " cannot use the 'begin' or 'end' modifiers (B/E) \n"; print; clear; quit; } "}*command*" { push; push; add "error near line "; ll; add " of script: extra closing brace '}' ?. \n"; print; clear; quit; } "comment*{*" { push; push; add "error near line "; ll; add " of script: comments cannot occur between \n"; add " a test and a brace ({). \n"; print; clear; quit; } #------------ # the .restart command just jumps to the start: label # (which is usually followed by a "read" command) # but '.' is also the AND concatenator, which seems ambiguous, # but the parsing works. ".*word*" { clear; ++; get; --; "restart" { clear; add "jump start"; put; clear; add "command*"; push; .reparse } "reparse" { clear; add "jump parse"; put; clear; add "command*"; push; .reparse } push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script: \n"; add " misplaced dot '.' (use for AND logic or in .reparse/.restart \n"; print; clear; quit; } #----------------------------------------- # compiling comments so as to transfer them to the compiled # file. # implement these rules to conserve comments "comment*command*","command*comment*","commandset*comment*" { clear; get; add "\n"; ++; get; --; put; clear; add "command*"; push; .reparse } "comment*comment*" { clear; get; add "\n"; ++; get; --; put; clear; add "comment*"; push; .reparse } # ----------------------- # negated tokens. # # This is a new more elegant way to negate a whole set of # tests (tokens) where the negation logic is stored on the # stack, not in the current tape cell. We just add "not" to # the stack token. # eg: ![:alpha:] ![a-z] ![abcd] !"abc" !B"abc" !E"xyz" # This format is used to indicate a negative test for # a brace block. eg: ![aeiou] { add "< not a vowel"; print; clear; } "!*quote*","!*class*","!*begintext*", "!*endtext*", "!*eof*","!*tapetest*" { # a simplification: just replace the token name with its # negative. replace "!*" "not"; push; # now get the token-value # added an extra ++ here. get; --; put; ++; clear; .reparse } #----------------------------------------- # format: E"text" or E'text' # This format is used to indicate a "workspace-ends-with" text before # a brace block. "E*quote*" { clear; add "endtext*"; push; get; --; put; ++; clear; .reparse } #----------------------------------------- # format: B"sometext" or B'sometext' # A 'B' preceding some quoted text is used to indicate a # 'workspace-begins-with' test, before a brace block. "B*quote*" { clear; add "begintext*"; push; get; --; put; ++; clear; .reparse } #-------------------------------------------- # ebnf: command := word, ';' ; # formats: "pop; push; clear; print; " etc # all commands need to end with a semi-colon except for # .reparse and .restart # "word*;*" { clear; # check if command requires parameter get; "add", "until", "while", "whilenot", "mark", "go", "escape", "unescape", "delim", "replace" { put; clear; add "Pep: '"; get; add "'"; add " << command needs an argument, on line "; ll; add " of script.\n"; print; clear; quit; } clear; add "command*"; # no need to format tape cells because current cell contains word push; .reparse } #----------------------------------------- # ebnf: commandset := command , command ; "command*command*", "commandset*command*" { clear; add "commandset*"; push; # format the tape attributes. Add the next command on a newline --; get; add "\n"; ++; get; --; put; ++; clear; .reparse } #------------------- # here we begin to parse "test*" and "ortestset*" and "andtestset*" # #------------------- # eg: B"abc" {} or E"xyz" {} "begintext*{*","endtext*{*","quote*{*","class*{*", "eof*{*","tapetest*{*" { # set accumulator == 0 zero; B"begin" { clear; add "testbegins "; } B"end" { clear; add "testends "; } B"quote" { clear; add "testis "; } B"class" { clear; add "testclass "; } # clear the tapecell for testeof and testtape because # they take no arguments. B"eof" { clear; put; add "testeof "; } B"tapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumptrue 2 \n"; # this extra jump has utility when we parse ortestsets and # andtestsets. add "jump block.end."; # the final jumpfalse + target will be added when # "test*{*commandset*}*" is parsed, or when # "ortestset*{*commandset*}*" # "andtestset*{*commandset*}*" put; a+; a+; a+; a+; clear; add "test*{*"; push; push; .reparse } #------------------- # negated tests # eg: !B"xyz {} # !E"xyz" {} # !"abc" {} # ![a-z] {} "notbegintext*{*","notendtext*{*","notquote*{*","notclass*{*", "noteof*{*","nottapetest*{*" { # set accumulator == 0 zero; B"notbegin" { clear; add "testbegins "; } B"notend" { clear; add "testends "; } B"notquote" { clear; add "testis "; } B"notclass" { clear; add "testclass "; } # clear the tapecell for testeof and testtape because # they take no arguments. B"noteof" { clear; put; add "testeof "; } B"nottapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumpfalse 2 \n"; # this extra jump has utility when we parse ortestsets and # andtestsets. add "jump block.end."; # the final jumpfalse + target will be added later # use the accumulator to store the incremented jump target put; a+; a+; a+; a+; clear; add "test*{*"; push; push; .reparse } #------------------- # 3 tokens #------------------- pop; #----------------------------- # some 3 token errors!!! # there are many other of these errors but I am not going # to write them all. "{*begintext*;*","{*endtext*;*","{*class*;*" { push; push; push; add "error near line "; ll; add " (char "; cc; add ")"; add " of script (misplaced semicolon?) \n"; print; clear; quit; } "{*quote*;*","commandset*quote*;*","command*quote*;*" { push; push; push; add "[error] near line "; ll; add " (char "; cc; add ")"; add " of script (quoted text without a command?) \n"; print; clear; quit; } # to simplify subsequent tests, transmogrify a single command # to a commandset (multiple commands). "{*command*}*" { clear; add "{*commandset*}*"; push; push; push; .reparse } # rule #',' ortestset ::= ',' test '{' # trigger a transmogrification from test to ortestset token # and # '.' andtestset ::= '.' test '{' ",*test*{*" { clear; add ",*ortestset*{*"; push; push; push; .reparse } # trigger a transmogrification from "test" to "andtest" by # looking backwards in the stack ".*test*{*" { # the jump counter is 1 too high for AND tests a-; clear; add ".*andtestset*{*"; push; push; push; .reparse } # errors! mixing AND and OR concatenation ",*andtestset*{*", ".*ortestset*{*" { # push the tokens back to make debugging easier push; push; push; add " error: mixing AND (.) and OR (,) concatenation in \n"; add " in script near line "; ll; add " (character "; cc; add ") \n"; print; clear; quit; } #-------------------------------------------- # ebnf: command := keyword , quoted-text , ";" ; # format: add "text"; "word*quote*;*" { clear; get; "replace" { # error add "< command requires 2 parameters, not 1 \n"; add "near line "; ll; add " of script. \n"; print; clear; quit; } "add", "until", "while", "whilenot", "escape", "mark", "go", "unescape", "delim" { # check here or in error.pss for multiline quoted arguments # for "mark" "go" "until" etc because they are not allowed. clear; add "command*"; push; # a command plus argument, eg add "this" --; get; # allow multiline text in (only) the add command # we do this by turning a multiline "add" command into a # sequence of single line "add" commands (because that is what # the assembler format allows). Actually, I could just write # replace "\n" "\\n"; which should work but would be much less # readable in the assembled file. "add" { add " "; ++; get; replace "\n" '\\n"\nadd "'; --; put; ++; clear; .reparse } # maybe it would be useful for the until command to # allow multiline as well "until" { add " "; ++; get; replace "\n" '\\n'; --; put; ++; clear; .reparse } add " "; ++; get; --; put; ++; clear; .reparse } # error, superfluous argument add ": command does not take an argument \n"; add "near line "; ll; add " of script. \n"; print; #state quit; } #---------------------------------- # format: "while [:alpha:] ;" or whilenot [a-z] ; "word*class*;*" { clear; get; "while", "whilenot" { clear; add "command*"; push; # a command plus argument, eg while [a-z] --; get; add " "; ++; get; --; put; ++; clear; .reparse } # error add " < command cannot have a class argument \n"; add "line "; ll; add ": error in script \n"; print; clear; quit; } # ------------------------------- # 4 tokens # ------------------------------- pop; #------------------------------------- # ebnf: command := replace , quote , quote , ";" ; # example: replace "and" "AND" ; "word*quote*quote*;*" { clear; get; "replace" { clear; add "command*"; push; #--------------------------- # a command plus 2 arguments, eg replace "this" "that" --; get; add " "; ++; get; add " "; ++; get; --; --; put; ++; clear; .reparse } add " << command does not take 2 quoted arguments. \n"; add " on line "; ll; add " of script.\n"; print; quit; } #------------------------------------- # format: begin { #* commands *# } # "begin" blocks which are only executed once (they # will are assembled before the "start:" label. They must come before # all other commands. # "begin*{*command*}*", "begin*{*commandset*}*" { clear; ++; ++; get; --; --; put; clear; add "beginblock*"; push; .reparse } # ------------- # parses and compiles concatenated tests # eg: 'a',B'b',E'c',[def],[:space:],[g-k] { ... "begintext*,*ortestset*{*", "endtext*,*ortestset*{*", "quote*,*ortestset*{*", "class*,*ortestset*{*", "eof*,*ortestset*{*", "tapetest*,*ortestset*{*" { B"begin" { clear; add "testbegins "; } B"end" { clear; add "testends "; } B"quote" { clear; add "testis "; } B"class" { clear; add "testclass "; } # clear the tapecell for testeof and testtape because # they take no arguments. B"eof" { clear; put; add "testeof "; } B"tapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumptrue "; count; add "\n"; ++; ++; get; --; --; put; clear; # this works as long as we dont mix AND and OR concatenations # add "test*{*"; # need to change to this add "ortestset*{*"; push; push; a+; a+; .reparse } # A collection of negated tests. "notbegintext*,*ortestset*{*", "notendtext*,*ortestset*{*", "notquote*,*ortestset*{*", "notclass*,*ortestset*{*", "noteof*,*ortestset*{*", "nottapetest*,*ortestset*{*" { B"notbegin" { clear; add "testbegins "; } B"notend" { clear; add "testends "; } B"notquote" { clear; add "testis "; } B"notclass" { clear; add "testclass "; } B"noteof" { clear; put; add "testeof "; } B"nottapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumpfalse "; count; add "\n"; ++; ++; get; --; --; put; clear; # this works as long as we dont mix AND and OR concatenations add "ortestset*{*"; # need to change to this # add "ortestset*{*"; push; push; a+; a+; .reparse } # this works as long as we dont mix AND and OR concatenations # ------------- # AND logic # parses and compiles concatenated AND tests # eg: 'a',B'b',E'c',[def],[:space:],[g-k] { ... # it is possible to elide this block with the negated block # for compactness but maybe readability is not as good. "begintext*.*andtestset*{*", "endtext*.*andtestset*{*", "quote*.*andtestset*{*", "class*.*andtestset*{*", "eof*.*andtestset*{*", "tapetest*.*andtestset*{*" { B"begin" { clear; add "testbegins "; } B"end" { clear; add "testends "; } B"quote" { clear; add "testis "; } B"class" { clear; add "testclass "; } B"eof" { clear; put; add "testeof "; } B"tapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumpfalse "; count; add "\n"; ++; ++; get; --; --; put; clear; add "andtestset*{*"; push; push; a+; a+; .reparse } # eg # negated tests concatenated with AND logic (.). The # negated tests can be chained with non negated tests. # eg: B'http' . !E'.txt' { ... } "notbegintext*.*andtestset*{*", "notendtext*.*andtestset*{*", "notquote*.*andtestset*{*", "notclass*.*andtestset*{*", "noteof*.*andtestset*{*", "nottapetest*.*andtestset*{*" { B"notbegin" { clear; add "testbegins "; } B"notend" { clear; add "testends "; } B"notquote" { clear; add "testis "; } B"notclass" { clear; add "testclass "; } B"noteof" { clear; put; add "testeof "; } B"nottapetest" { clear; put; add "testtape "; } get; add "\n"; add "jumptrue "; count; add "\n"; ++; ++; get; --; --; put; clear; add "andtestset*{*"; push; push; a+; a+; .reparse } #------------------------------------- # we should not have to check for the {*command*}* pattern # because that has already been transformed to {*commandset*}* "test*{*commandset*}*", "andtestset*{*commandset*}*", "ortestset*{*commandset*}*" { # indent the assembled code for readability B"test*{*" { clear; # get rid of unnecessary jump but only in "test" cases get; # for positive tests (eg [a-z] {...}) replace "jumptrue 2 \njump" "jumpfalse"; put; # for negative tests (eg ![a-z] {...}) replace "jumpfalse 2 \njump" "jumptrue"; put; } clear; ++; ++; add " "; get; replace "\n" "\n "; put; --; --; clear; get; # the final jump (to the closing brace) has already been # coded in the "test*{*" rule or the other rules. # we just need to add the label number with "cc" cc; add "\n"; ++; ++; get; add "\nblock.end."; cc; add ":"; --; --; put; clear; add "command*"; push; # always reparse/compile .reparse } # ------------- # multi-token end-of-stream errors # not a comprehensive list of errors... (eof) { E"begintext*",E"endtext*",E"test*",E"ortestset*",E"andtestset*" { add " Error near end of script at line "; ll; add ". Test with no brace block? \n"; print; clear; quit; } E"quote*",E"class*",E"word*"{ put; clear; add "Error end of script! (line "; ll; add ") missing semi-colon? \n"; add "Parse stack: "; get; add "\n"; print; clear; quit; } E"{*", E"}*", E";*", E",*", E".*", E"!*", E"B*", E"E*" { put; clear; add "Error: misplaced terminal character at end of script! (line "; ll; add "). \n"; add "Parse stack: "; get; add "\n"; print; clear; quit; } } # put the 4 (or less) tokens back on the stack push; push; push; push; (eof) { #add "end of script!! \n" print; clear; #--------------------- # check if the script correctly parsed (there should only # be one token on the stack, namely "commandset*" or "command*" pop; pop; "commandset*", "command*" { push; --; add "# Assembled with the script 'compile.pss' \n"; add "start:\n"; get; # an extra space because of a bug in compile() add "\njump start \n"; # put a copy of the final compilation into the tapecell # so it can be inspected interactively. put; # remove this print from asm.pp after generating a new asm.pp # with pep -f compile.pss compile.pss > asm.new.pp; cp asm.new.pp asm.pp print; # remove! # save the compiled script to 'sav.pp' write; clear; quit; } "beginblock*commandset*", "beginblock*command*" { clear; add "# Assembled with the script 'compile.pss' \n"; get; add "\n"; ++; add "start:\n"; get; # an extra space because of a bug in compile() add "\njump start \n"; # put a copy of the final compilation into the tapecell # so it can be inspected interactively. put; # remove this 'print' from asm.pp after generating a new asm.pp # with pep -f compile.pss compile.pss > asm.new.pp; cp asm.new.pp asm.pp print; # remove! # also save the compiled script to 'sav.pp' write; clear; quit; } push; push; # state clear; add "After compiling with 'compile.pss' (at EOF): \n "; add " parse error in input script, check syntax: \n "; add " To debug script try the -I switch with \n "; add " >> pep -If script -i 'some input' \n "; add " or to debug the compilation process try: \n "; add " >> pep -Ia asm.pp script' \n "; print; clear; # clear sav.pp because script could not be compiled write; # bail means exit with error bail; } # not eof # there is an implicit .restart command here (jump start)