Useful task -- Character properties
On Tue, May 03, 2005 at 09:22:11PM +0100, Nicholas Clark wrote: Whilst I confess that it's unlikely to be me here, if anyone has the time to contribute some help, do you have a list of useful self-contained tasks that people might be able to take on? Actually, overnight I realized there's a relatively good-sized project that needs figuring out -- identifying character properties such as isalpha, islower, isprint, etc. Here I'll briefly sketch how I'd like it to work, and maybe someone enterprising can take things from there for us. Currently Parrot offers quite a few ops for character properties -- namely is_whitespace, is_wordchar, is_digit, etc. and their find_XXX counterparts. While these are useful, the set is also incomplete -- at the moment I haven't found anything that let's us find alphabetic, uppercase, lowercase, etc. properties. (If I've just overlooked something, please point it out!) I suppose Parrot could add a bunch of new is_alpha, is_upper, is_lower, etc. ops, but having separate opcodes for every property actually complicates the design of PGE a fair bit as well as makes a lot of very function-specific opcodes. What would *really* be useful would be to have three basic opcodes: is_cclass(out INT, in INT, in STR, in INT) Set $1 to 1 if the codepoint of $3 at position $4 is in the character class(es) given by $2. find_cclass(out INT, in INT, in STR, in INT, in INT) Set $1 to the offset of the first codepoint matching the character class(es) given by $2 in string $3, starting at offset $4 for up to $5 codepoints. If no matching character is found, set $1 to -1. find_not_cclass(out INT, in INT, in STR, in INT, in INT) Set $1 to the offset of the first codepoint not matching the character class(es) given by $2 in string $3, starting at offset $4 for up to $5 codepoints. If the substring consists entirely of matching characters, set $1 to -1. The character classes in $2 above are given by an integer bitmask, defined according to the following table (or something like it -- I took this table from ctype.h on my system, then added a newline class): 0x0001 - uppercase char 0x0002 - lowercase char 0x0004 - alphabetic char 0x0008 - numeric character 0x0010 - hexadecimal digit 0x0020 - whitespace 0x0040 - printing 0x0080 - graphical 0x0100 - blank (i.e., SPC and TAB) 0x0200 - control character 0x0400 - punctuation character 0x0800 - alphanumeric character 0x1000 - newline character We have 32 bits available, so we could extend this table as needed. And EVENTUALLY we'll probably need a more general interface to handle Unicode properties as well as character class compositions, but I speculate that we can do those either in a library, or (if speed is needed) we can build a character class PMC type optimized for charsets and have: is_cclass(out INT, in PMC, in STR, in INT) find_cclass(out INT, in PMC, in STR, in INT, in INT) find_not_cclass(out INT, in PMC, in STR, in INT, in INT) But for now the integer representation of character classes ought to be sufficient. Anyway, that's another very useful self-contained task that I'd be glad to have a volunteer for. Pm
Re: Useful task -- Character properties
At 10:21 AM -0500 5/4/05, Patrick R. Michaud wrote: On Tue, May 03, 2005 at 09:22:11PM +0100, Nicholas Clark wrote: Whilst I confess that it's unlikely to be me here, if anyone has the time to contribute some help, do you have a list of useful self-contained tasks that people might be able to take on? Actually, overnight I realized there's a relatively good-sized project that needs figuring out -- identifying character properties such as isalpha, islower, isprint, etc. Here I'll briefly sketch how I'd like it to work, and maybe someone enterprising can take things from I'd planned on everything else going into constructed character classes. I'd figured the named classes would correspond to the major regex classes (things represented by \X sequences) while the constructed classes would handle everything else and more or less correspond to [] style sequences. I thought I'd put in some docs to that effect, but apparently not. :( -- Dan --it's like this--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: Useful task -- Character properties
On Wed, May 04, 2005 at 12:30:48PM -0400, Dan Sugalski wrote: At 10:21 AM -0500 5/4/05, Patrick R. Michaud wrote: Actually, overnight I realized there's a relatively good-sized project that needs figuring out -- identifying character properties such as isalpha, islower, isprint, etc. Here I'll briefly sketch how I'd like it to work, and maybe someone enterprising can take things from I'd planned on everything else going into constructed character classes. I'd figured the named classes would correspond to the major regex classes (things represented by \X sequences) while the constructed classes would handle everything else and more or less correspond to [] style sequences. Makes sense. But somehow the named class versions of the ops don't give me quite as much coverage as I'd like -- for example, I can use find_digit to measure off a sequence of non-digit characters (e.g., rx { \D* } ), but there's not a corresponding find_non_digit opcode to let me measure off a set of digits (e.g., rx { \d* } ). We'll still need a way to make constructed character classes for upper, lower, and the like. But I (or someone else) can probably build that component in PIR for now, just hardcoding the ASCII or Latin-1 tables for the time being until we come up with something else later. Pm
Re: Useful task -- Character properties
Patrick R. Michaud wrote: [ see below for some more ] Actually, overnight I realized there's a relatively good-sized project that needs figuring out -- identifying character properties such as isalpha, islower, isprint, etc. Here I'll briefly sketch how I'd like it to work, and maybe someone enterprising can take things from there for us. Currently Parrot offers quite a few ops for character properties -- namely is_whitespace, is_wordchar, is_digit, etc. and their find_XXX counterparts. While these are useful, the set is also incomplete -- at the moment I haven't found anything that let's us find alphabetic, uppercase, lowercase, etc. properties. (If I've just overlooked something, please point it out!) I suppose Parrot could add a bunch of new is_alpha, is_upper, is_lower, etc. ops, but having separate opcodes for every property actually complicates the design of PGE a fair bit as well as makes a lot of very function-specific opcodes. What would *really* be useful would be to have three basic opcodes: is_cclass(out INT, in INT, in STR, in INT) Set $1 to 1 if the codepoint of $3 at position $4 is in the character class(es) given by $2. find_cclass(out INT, in INT, in STR, in INT, in INT) Set $1 to the offset of the first codepoint matching the character class(es) given by $2 in string $3, starting at offset $4 for up to $5 codepoints. If no matching character is found, set $1 to -1. find_not_cclass(out INT, in INT, in STR, in INT, in INT) Set $1 to the offset of the first codepoint not matching the character class(es) given by $2 in string $3, starting at offset $4 for up to $5 codepoints. If the substring consists entirely of matching characters, set $1 to -1. The character classes in $2 above are given by an integer bitmask, defined according to the following table (or something like it -- I took this table from ctype.h on my system, then added a newline class): 0x0001 - uppercase char 0x0002 - lowercase char 0x0004 - alphabetic char 0x0008 - numeric character 0x0010 - hexadecimal digit 0x0020 - whitespace 0x0040 - printing 0x0080 - graphical 0x0100 - blank (i.e., SPC and TAB) 0x0200 - control character 0x0400 - punctuation character 0x0800 - alphanumeric character 0x1000 - newline character We have 32 bits available, so we could extend this table as needed. And EVENTUALLY we'll probably need a more general interface to handle Unicode properties as well as character class compositions, but I speculate that we can do those either in a library, or (if speed is needed) we can build a character class PMC type optimized for charsets and have: is_cclass(out INT, in PMC, in STR, in INT) find_cclass(out INT, in PMC, in STR, in INT, in INT) find_not_cclass(out INT, in PMC, in STR, in INT, in INT) But for now the integer representation of character classes ought to be sufficient. For hysterical raisins we actually have already two of char class interfaces (partially) implemented, e.g. src/string.c: Parrot_string_is_digit(Interp *interpreter, STRING *s, INTVAL offset) src/string_primitives.c Parrot_char_is_digit(Interp *interpreter, UINTVAL character) The former is covered by an opocde in ops/string.ops and is the more useful form taking an string and an offset. The latter OTOH can call the ICU function, if ICU is present. To cleanup that mess, we stick to Patricks plan, which implies in no specific order: - implement the new opcodes, first in experimental.ops - create an enum of the char classes in charset.h - create the general API in that header too - convert existing charset classifying tables to the new bits - move the ICU functions to charset/unicode.c - deprecate existing opcodes and APIs - cleanup string_primitives.* - convert existing tests - write new tests - write more news tests - all I've forgotten to list See also: src/ string.c string_primitives.c include/parrot/ charset.h string_primitives.h string_funcs.h charset/ *.c *.h [1] ops/ string.ops t op/string_cs.t [1] especially char typetable[] and usage of it Anyway, that's another very useful self-contained task that I'd be glad to have a volunteer for. Yep. Pm leo