Name
Unisyn::Parse - Parse a Unisyn expression.
Synopsis
Parse the Unisyn expression:
𝗮𝑎𝗯which assigns b to a. Parse this expression and print the resulting parse tree:
my $address = Rutf8 $Lex->{sampleText}{vav}; # Source in utf8
my $size = StringLength V(string, $address); # Length of source
my $parse = create K(address, $address), $size; # Create parse tree from source
$parse->print; # Print parse treeTo get:
ok Assemble(debug=>0, eq => <<END); # Assemble and run
Assign: 𝑎
Term
Variable: 𝗮
Term
Variable: 𝗯
ENDDescription
Parse a Unisyn expression.
Version "20210818".
The following sections describe the methods in each functional area of this module. For an alphabetic listing of all methods by name see Index.
Create
Create a Unisyn parse of a utf8 string.
create($address, $size)
Create a new unisyn parse from a utf8 string
Parameter Description
1 $address Address of utf8 source string to parse as a variable
2 $size Length of string as a variableExample:
my $address = Rutf8 $Lex->{sampleText}{vav}; # Source in utf8
my $size = StringLength V(string, $address); # Length of source
my $parse = create K(address, $address), $size; # Create parse tree from source # 𝗘𝘅𝗮𝗺𝗽𝗹𝗲
$parse->print; # Print parse tree
ok Assemble(debug=>0, eq => <<END);
Assign
Term
Variable
Term
Variable
ENDParse
Parse Unisyn expressions
Print a parse tree
print($parse)
Create a parser for an expression:
𝗮 = 𝗯by coding:
my $address = Rutf8 $Lex->{sampleText}{vav}; # Source in utf8
my $size = StringLength V(string, $address); # Length of source
my $parse = create K(address, $address), $size; # Create parse tree from source
$parse->print; # Print parse tree # 𝗘𝘅𝗮𝗺𝗽𝗹𝗲Parse the Unisyn expression to get:
ok Assemble(debug=>0, eq => <<END);
Assign
Term
Variable: 𝗮
Term
Variable: 𝗯
ENDHash Definitions
Unisyn::Parse Definition
Description of parse
Output fields
address
Address of source string as utf8
arena
Arena containing tree
fails
Number of failures encountered in this parse
parse
Offset to the head of the parse tree
size
Size of source string as utf8
Private Methods
getAlpha($register, $address, $index)
Load the position of a lexical item in its alphabet from the current character.
Parameter Description
1 $register Register to load
2 $address Address of start of string
3 $index Index into stringgetLexicalCode($register, $address, $index)
Load the lexical code of the current character in memory into the specified register.
Parameter Description
1 $register Register to load
2 $address Address of start of string
3 $index Index into stringputLexicalCode($register, $address, $index, $code)
Put the specified lexical code into the current character in memory.
Parameter Description
1 $register Register used to load code
2 $address Address of string
3 $index Index into string
4 $code Code to putloadCurrentChar()
Load the details of the character currently being processed so that we have the index of the character in the upper half of the current character and the lexical type of the character in the lowest byte.
checkStackHas($depth)
Check that we have at least the specified number of elements on the stack.
Parameter Description
1 $depth Number of elements required on the stackpushElement()
Push the current element on to the stack.
pushEmpty()
Push the empty element on to the stack.
lexicalNameFromLetter($l)
Lexical name for a lexical item described by its letter.
Parameter Description
1 $l Letter of the lexical itemlexicalNumberFromLetter($l)
Lexical number for a lexical item described by its letter.
Parameter Description
1 $l Letter of the lexical itemnew($depth, $description)
Create a new term in the parse tree rooted on the stack.
Parameter Description
1 $depth Stack depth to be converted
2 $description Text reason why we are creating a new termerror($message)
Die.
Parameter Description
1 $message Error messagetestSet($set, $register)
Test a set of items, setting the Zero Flag is one matches else clear the Zero flag.
Parameter Description
1 $set Set of lexical letters
2 $register Register to testcheckSet($set)
Check that one of a set of items is on the top of the stack or complain if it is not.
Parameter Description
1 $set Set of lexical lettersreduce($priority)
Convert the longest possible expression on top of the stack into a term at the specified priority.
Parameter Description
1 $priority Priority of the operators to reducereduceMultiple($priority)
Reduce existing operators on the stack.
Parameter Description
1 $priority Priority of the operators to reduceaccept_a()
Assign.
accept_b()
Open.
accept_B()
Closing parenthesis.
accept_d()
Infix but not assign or semi-colon.
accept_p()
Prefix.
accept_q()
Post fix.
accept_s()
Semi colon.
accept_v()
Variable.
parseExpressionCode()
Parse the string of classified lexical items addressed by register $start of length $length. The resulting parse tree (if any) is returned in r15.
parseExpression(@parameters)
Create a parser for an expression described by variables.
Parameter Description
1 @parameters Parameters describing expressionMatchBrackets(@parameters)
Replace the low three bytes of a utf32 bracket character with 24 bits of offset to the matching opening or closing bracket. Opening brackets have even codes from 0x10 to 0x4e while the corresponding closing bracket has a code one higher.
Parameter Description
1 @parameters ParametersClassifyNewLines(@parameters)
Scan input string looking for opportunities to convert new lines into semi colons.
Parameter Description
1 @parameters ParametersClassifyWhiteSpace(@parameters)
Classify white space per: "lib/Unisyn/whiteSpace/whiteSpaceClassification.pl".
Parameter Description
1 @parameters ParametersparseUtf8($p, @parameters)
Parse a unisyn expression encoded as utf8 and return the parse tree.
Parameter Description
1 $p Parse
2 @parameters ParametersT($key, $expected, %options)
Test a parse.
Parameter Description
1 $key Key of text to be parsed
2 $expected Expected result
3 %options OptionsIndex
1 accept_a - Assign.
2 accept_B - Closing parenthesis.
3 accept_b - Open.
4 accept_d - Infix but not assign or semi-colon.
5 accept_p - Prefix.
6 accept_q - Post fix.
7 accept_s - Semi colon.
8 accept_v - Variable.
9 checkSet - Check that one of a set of items is on the top of the stack or complain if it is not.
10 checkStackHas - Check that we have at least the specified number of elements on the stack.
11 ClassifyNewLines - Scan input string looking for opportunities to convert new lines into semi colons.
12 ClassifyWhiteSpace - Classify white space per: "lib/Unisyn/whiteSpace/whiteSpaceClassification.
13 create - Create a new unisyn parse from a utf8 string
14 error - Die.
15 getAlpha - Load the position of a lexical item in its alphabet from the current character.
16 getLexicalCode - Load the lexical code of the current character in memory into the specified register.
17 lexicalNameFromLetter - Lexical name for a lexical item described by its letter.
18 lexicalNumberFromLetter - Lexical number for a lexical item described by its letter.
19 loadCurrentChar - Load the details of the character currently being processed so that we have the index of the character in the upper half of the current character and the lexical type of the character in the lowest byte.
20 MatchBrackets - Replace the low three bytes of a utf32 bracket character with 24 bits of offset to the matching opening or closing bracket.
21 new - Create a new term in the parse tree rooted on the stack.
22 parseExpression - Create a parser for an expression described by variables.
23 parseExpressionCode - Parse the string of classified lexical items addressed by register $start of length $length.
24 parseUtf8 - Parse a unisyn expression encoded as utf8 and return the parse tree.
25 print - Create a parser for an expression described by variables.
26 pushElement - Push the current element on to the stack.
27 pushEmpty - Push the empty element on to the stack.
28 putLexicalCode - Put the specified lexical code into the current character in memory.
29 reduce - Convert the longest possible expression on top of the stack into a term at the specified priority.
30 reduceMultiple - Reduce existing operators on the stack.
31 T - Test a parse.
32 testSet - Test a set of items, setting the Zero Flag is one matches else clear the Zero flag.
Installation
This module is written in 100% Pure Perl and, thus, it is easy to read, comprehend, use, modify and install via cpan:
sudo cpan install Unisyn::ParseAuthor
Copyright
Copyright (c) 2016-2021 Philip R Brenan.
This module is free software. It may be used, redistributed and/or modified under the same terms as Perl itself.