crystcif-parse/lib/tokens.js

A parser for crystallographic CIF files

'use strict';

/* Rules taken from the technical specification for CIF 1.1 as seen at:

    https://www.iucr.org/resources/cif/spec/version1.1/cifsyntax
*/

/* CIF format standard tokens in RegExp form

These Regular Expressions are meant to embody the standard syntax of CIF
files as found at the URL above. However, they will not all be used in
practice, as some needed features (especially the look-behind assertions) are
relatively new and may not be supported for all users.

*/


var sp = ' ';
var ht = '\\t';
var eol = '\\r*\\n';

module.exports.end_of_line = eol;

/*

<OrdinaryChar>:

{ '!' | '%' | '&' | '(' | ')' | '*' | '+' | ',' | '-' | '.' | '/' | '0' | '1' 
| '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | ':' | '<' | '=' | '>' | '?' 
| '@' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' | 'K' | 'L' 
| 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' | 'T' | 'U' | 'V' | 'W' | 'X' | 'Y' 
| 'Z' | '\' | '^' | '`' | 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'g' | 'h' | 'i' 
| 'j' | 'k' | 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' | 's' | 't' | 'u' | 'v' 
| 'w' | 'x' | 'y' | 'z' | '{' | '|' | '}' | '~' }
 */
var ordinary_char = "a-zA-Z0-9!%&\(\)*+,\-.\\/:<=>\?@\\^`\{\¦\}~";
module.exports.ordinary_char = "[" + ordinary_char + "]";
/*

<NonBlankChar>:

<OrdinaryChar> | <double_quote> | '#' | '$' | <single_quote> | '_' |';' | '[' 
| ']' 
 */
var nonblank_char = ordinary_char + "\"#$'_;\\[\\]";
module.exports.nonblank_char = "[" + nonblank_char + "]";
// These variations are useful for strings with quotes
var nonblank_char_nosingle = ordinary_char + "\"#$_;\\[\\]";
var nonblank_char_nodouble = ordinary_char + "#$'_;\\[\\]";
/*

<TextLeadChar>:

<OrdinaryChar> | <double_quote> | '#' | '$' | <single_quote> | '_' | <SP> | 
<HT> |'[' | ']' 
 */
var textlead_char = ordinary_char + "\"#$'_\\[\\]" + sp + ht;
module.exports.textlead_char = "[" + textlead_char + "]";
/*

<AnyPrintChar>:

<OrdinaryChar> | <double_quote> | '#' | '$' | <single_quote> | '_' | <SP> |
<HT> | ';' | '[' | ']'  
 */
var anyprint_char = nonblank_char + sp + ht;
module.exports.anyprint_char = "[" + anyprint_char + "]";
/*

<Digit>

{ '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' }
 */
var digit = '0-9';
module.exports.digit = "[" + digit + "]";
/*

<Comments>

{ '#' {<AnyPrintChar>}* <eol>}+ 
 */
var comments = "(?:#[" + anyprint_char + "]*" + eol + ")+";
module.exports.comments = comments;
/*

<TokenizedComments>

{ <SP> | <HT> | <eol> |}+ <Comments>    
 */
var tok_comments = "[" + sp + ht + eol + "]+" + comments;
module.exports.tok_comments = tok_comments;
/*

<WhiteSpace>

{ <SP> | <HT> | <eol> | <TokenizedComments>}+   
 */
var whitespace = "(?:" + tok_comments + "|" + sp + "|" + ht + "|" + eol +
    ")+";
module.exports.whitespace = whitespace;
/*

<SemiColonTextField>

';' { {<AnyPrintChar>}* <eol>
{{<TextLeadChar> {<AnyPrintChar>}*}? <eol>}*
} ';'
 */
var semicolontext = ";[" + anyprint_char + "]*" + eol +
    "(?:(?:[" + textlead_char + "][" + anyprint_char + "]*)?" + eol + ")*;";
module.exports.semicolontext = semicolontext;
/*

<SingleQuotedString>

<single_quote>{<AnyPrintChar>}* <single_quote>
 */
var squotestring = "'[" + nonblank_char_nosingle + sp + ht + "]*'";
module.exports.squotestring = squotestring;
/*

<DoubleQuotedString>

<double_quote>{<AnyPrintChar>}* <double_quote>
 */
var dquotestring = '"[' + nonblank_char_nodouble + sp + ht + ']*"';
module.exports.dquotestring = dquotestring;
/* 

<UnquotedString>

<eol><OrdinaryChar> {<NonBlankChar>}*   
or 
<eol><OrdinaryChar> {<NonBlankChar>}*   
<noteol>{<OrdinaryChar>|';'} {<NonBlankChar>}

NOTE: this is troublesome because in theory it requires lookbehinds.
We will try not to use it in practice. This is an approximation
**/
var uquotestring = "[" + eol + sp + ht + "][" + ordinary_char + "][" +
    nonblank_char + "]*";
module.exports.uquotestring = uquotestring;
/*

<QuotedString> 

<SingleQuotedString> | <DoubleQuotedString>
*/
var quotestring = "(?:" + squotestring + "|" + dquotestring + ")";
module.exports.quotestring = quotestring;
/*

<CharString>

<UnquotedString> | <SingleQuotedString> | <DoubleQuotedString>  
 */
var chrstring = "(?:" + squotestring + "|" + dquotestring + "|" +
    uquotestring + ")";
module.exports.chrstring = chrstring;
/*

<UnsignedInteger>

{ <Digit> }+
 */
var unsigned_int = "[" + digit + "]+";
module.exports.unsigned_int = unsigned_int;
/*

<Integer>

{ '+' | '-' }? <UnsignedInteger>
 */
var integer = "[+\-]?" + unsigned_int;
module.exports.integer = integer;
/*

<Exponent>

{ {'e' | 'E' } | {'e' | 'E' } { '+' | '- ' } } <UnsignedInteger>
 */
var exponent = "[eE]" + integer;
module.exports.exponent = exponent;
/*

<Float>

{ <Integer><Exponent> | { {'+'|'-'} ? { {<Digit>} * '.' <UnsignedInteger> } |
{ <Digit>} + '.' } } {<Exponent>} ? } }
 */
var float = "(?:(?:[+\-]?(?:[" + digit + "]*\\." + unsigned_int +
    "|[" + digit + "]+\\.)(?:" + exponent + ")?)|(?:" + integer +
    exponent + "))";
module.exports.float = float;
/*

<Number>

{<Integer> | <Float> }
 */
var number = "(?:" + float + "|" + integer + ")";
module.exports.number = number;
/*

<Numeric>

{ <Number> | <Number> '(' <UnsignedInteger> ')' }
 */
var numeric = "(?:(" + number + ")\\((" + unsigned_int + ")\\)|(" + number +
    "))";
module.exports.numeric = numeric;
/*

<Tag>

'_'{ <NonBlankChar>}+
 */
var tag = "_[" + nonblank_char + "]+";
module.exports.tag = tag;
/*

<Value> 

{ '.' | '?' | <Numeric> | <CharString> | <TextField> }
 */
var value = "(\\.|\\?|" + numeric + "|" + chrstring + "|" + semicolontext +
    ")";
module.exports.value = value;
/*

<LOOP_>

*/
var loop_kw = "[Ll][Oo][Oo][Pp]_";
module.exports.loop_kw = loop_kw;
/*

<LoopHeader>

<LOOP_> {<WhiteSpace> <Tag>}+
 */
var loop_header = loop_kw + "(" + whitespace + tag + ")+";
module.exports.loop_header = loop_header;
/*

<LoopBody>

<Value> { <WhiteSpace> <Value> }*   
 */
var loop_body = value + "(" + whitespace + value + ")*";
module.exports.loop_body = loop_body;
/*

<DataHeader>

<DATA_> { <NonBlankChar> }+
*/
var data_header = "[Dd][Aa][Tt][Aa]_[" + nonblank_char + "]+";
module.exports.data_header = data_header;
/*

<DataItem>

<Tag> <WhiteSpace> <Value> | <LoopHeader> <LoopBody>
 */
var data_item = "(?:(" + tag + ")" + whitespace + value + "|" + loop_header +
    loop_body + ")";
module.exports.data_item = data_item;
// Reserved keywords
module.exports.reserved = "(data|loop|global|save|stop)";

// Utility function to get ready regular expressions
module.exports.tokenRegex = function(tname, start, end, flags) {
    var flags = flags || 'g';
    if (tname == 'reserved') {
        flags = 'gi';
    }
    var restr = module.exports[tname];
    if (start) {
        restr = '^' + restr;
    }
    if (end) {
        restr = restr + '$';
    }
    return RegExp(restr, flags);
}