BS Contact J Specification

Annex B -
Grammar definition

B.1 Table of contents and introduction

B.1.1 Table of contents

This annex provides a detailed description of the grammar for each syntactic element in the Core X3D specification.
It is taken from the VRML 97 specification. The elements that aren't used in Core X3D are removed.
For compatibility with existing VRML 97 content, a Core X3D browser might silently ignore all nodes and fields that are not part of Core X3D.

The following table of contents lists the topics in this clause:

B.1 Table of contents and introduction
        B.1.1 Table of contents
        B.1.2 Introduction
B.2 General
B.3 Nodes
B.4 Fields

B.1.2 Introduction

It is not possible to parse X3D files using a context-free grammar. Semantic knowledge of the names and types of fields, eventIns, and eventOuts for each node type shall be used during parsing so that the parser knows which field type is being parsed.

The '#' (0x23) character begins a comment wherever it appears outside of the first line of the X3D file or quoted SFString or MFString fields. The '#' character and all characters until the next line terminator comprise the comment and are treated as whitespace.

The carriage return (0x0d), linefeed (0x0a), space (0x20), tab (0x09), and comma (0x2c) characters are whitespace characters wherever they appear outside of quoted SFString or MFString fields. Any number of whitespace characters and comments may be used to separate the syntactic entities of a VRML file. All reserved keywords are displayed in boldface type.

Any characters (including linefeed and '#') may appear within the quotes of SFString and MFString fields. A double quote character within a string shall be preceded with a backslash (e.g, "Each  double quotes character \" shall have a backslash."). A backslash character within a string shall be preceded with a backslash forming two backslashes (e.g., "One backslash \\ character").

Clause 6, Nodes reference, contains a description of the allowed fields, eventIns and eventOuts for all pre-defined node types. The double, float, and int32 symbols are expressed using Perl regular expression syntax. The IdFirstChar, IdRestChars, and string symbols have not been formally specified; Chapter 5, Fields and events reference, contains a more complete description of their syntax.

The following conventions are used in the semi-formal grammar specified in this clause:

1. Keywords and terminal symbols which appear literally in the X3D file, are specified in bold.
2. Nonterminal symbols used in the grammar are specified in italic.
3. Production rules begin with a nonterminal symbol and the sequence of characters "::=", and end with a semi-colon (";").
4. Alternation for production rules is specified using the vertical-bar symbol ("|").

Table B.1 contains the complete list of lexical elements for the grammar in this part of ISO/IEC 14772.

Table B.1 -- X3D lexical elements

Terminal symbols and the string symbol may be separated by one or more whitespace characters. Keywords and the Id, fieldType, float, int32, and double symbols shall be separated by one or more whitespace characters.

B.2 General

vrmlScene ::=

statements ;

statements ::=

statement |

statement statements |

empty ;

statement ::=

nodeStatement |

protoStatement |

routeStatement ;

nodeStatement ::=

node |

DEF nodeNameId node |

USE nodeNameId ;

rootNodeStatement ::=

node | DEF nodeNameId node ;

routeStatement ::=

ROUTE nodeNameId . eventOutId TO nodeNameId . eventInId ;

URLList ::=

mfstringValue ;

empty ::=

;

B.3 Nodes

node ::=

nodeTypeId { nodeBody }

nodeBody ::=

nodeBodyElement |

nodeBodyElement nodeBody |

empty ;

nodeBodyElement ::=

fieldId fieldValue |

fieldId IS fieldId |

eventInId IS eventInId |

eventOutId IS eventOutId |

routeStatement |

protoStatement ;

nodeNameId ::=

Id ;

nodeTypeId ::=

Id ;

fieldId ::=

Id ;

eventInId ::=

Id ;

eventOutId ::=

Id ;

Id ::=

IdFirstChar |

IdFirstChar IdRestChars ;

IdFirstChar ::=

Any ISO-10646 character encoded using UTF-8 except: 0x30-0x39, 0x0-0x20, 0x22, 0x23, 0x27, 0x2b, 0x2c, 0x2d, 0x2e, 0x5b, 0x5c, 0x5d, 0x7b, 0x7d, 0x7f ;

IdRestChars ::=

Any number of ISO-10646 characters except: 0x0-0x20, 0x22, 0x23, 0x27, 0x2c, 0x2e, 0x5b, 0x5c, 0x5d, 0x7b, 0x7d, 0x7f ;

B.4 Fields

fieldType ::=

MFColor |

MFFloat |

MFInt32 |

MFNode |

MFRotation |

MFString |

MFTime |

MFVec2f |

MFVec3f |

SFBool |

SFColor |

SFFloat |

SFInt32 |

SFNode |

SFRotation |

SFString |

SFTime |

SFVec2f |

SFVec3f ;

fieldValue ::=

sfboolValue |

sfcolorValue |

sffloatValue |

sfint32Value |

sfnodeValue |

sfrotationValue |

sfstringValue |

sftimeValue |

sfvec2fValue |

sfvec3fValue |

mfcolorValue |

mffloatValue |

mfint32Value |

mfnodeValue |

mfrotationValue |

mfstringValue |

mftimeValue |

mfvec2fValue |

mfvec3fValue ;

sfboolValue ::=

TRUE |

FALSE ;

sfcolorValue ::=

float float float ;

sffloatValue ::=

float ;

float ::=

([+/-]?((([0-9]+(\.)?)|([0-9]*\.[0-9]+))([eE][+\-]?[0-9]+)?)).

sfint32Value ::=

int32 ;

int32 ::=

([+\-]?(([0-9]+)|(0[xX][0-9a-fA-F]+)))

sfnodeValue ::=

nodeStatement |

NULL ;

sfrotationValue ::=

float float float float ;

sfstringValue ::=

string ;

string ::=

".*" ... double-quotes must be \", backslashes must be \\...

sftimeValue ::=

double ;

double ::=

([+/-]?((([0-9]+(\.)?)|([0-9]*\.[0-9]+))([eE][+\-]?[0-9]+)?))

mftimeValue ::=

sftimeValue |

[ ] |

[ sftimeValues ] ;

sftimeValues ::=

sftimeValue |

sftimeValue sftimeValues ;

sfvec2fValue ::=

float float ;

sfvec3fValue ::=

float float float ;

mfcolorValue ::=

sfcolorValue |

[ ] |

[ sfcolorValues ] ;

sfcolorValues ::=

sfcolorValue |

sfcolorValue sfcolorValues ;

mffloatValue ::=

sffloatValue |

[ ] |

[ sffloatValues ] ;

sffloatValues ::=

sffloatValue |

sffloatValue sffloatValues ;

mfint32Value ::=

sfint32Value |

[ ] |

[ sfint32Values ] ;

sfint32Values ::=

sfint32Value |

sfint32Value sfint32Values ;

mfnodeValue ::=

nodeStatement |

[ ] |

[ nodeStatements ] ;

nodeStatements ::=

nodeStatement |

nodeStatement nodeStatements ;

mfrotationValue ::=

sfrotationValue |

[ ] |

[ sfrotationValues ] ;

sfrotationValues ::=

sfrotationValue |

sfrotationValue sfrotationValues ;

mfstringValue ::=

sfstringValue |

[ ] |

[ sfstringValues ] ;

sfstringValues ::=

sfstringValue |

sfstringValue sfstringValues ;

mfvec2fValue ::=

sfvec2fValue |

[ ] |

[ sfvec2fValues] ;

sfvec2fValues ::=

sfvec2fValue |

sfvec2fValue sfvec2fValues ;

mfvec3fValue ::=

sfvec3fValue |

[ ] |

[ sfvec3fValues ] ;

sfvec3fValues ::=

sfvec3fValue |

sfvec3fValue sfvec3fValues ;