Changes between Version 3 and Version 4 of RFC59-Draft
- Timestamp:
- Aug 6, 2010, 8:56:40 AM (14 years ago)
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RFC59-Draft
v3 v4 7 7 8 8 A principle motivation for this work is to support OGC filter expressions in a single pass in a driver-independent manner. 9 10 All of the work detailed here is being prototyped in a sandbox, visit: 11 12 [http://svn.osgeo.org/mapserver/sandbox/sdlime/common-expressions/mapserver] 9 13 10 14 == Existing Expression Parsing == … … 67 71 '''Extending the Yacc grammar to support spatial operators''' 68 72 69 The mapserver.h definitions above allow for using shapeObj's within the Yacc grammar . There are two types of shape-related tokens: 1) a shape binding, that is, a reference to the geometry being evaluated and 2) shape literals, shapes described as WKT within the expression string. For example:73 The mapserver.h definitions above allow for using shapeObj's within the Yacc grammar (we also define a shapeObj as a new base token type within mapparser.y). There are two types of shape-related tokens: 1) a shape binding, that is, a reference to the geometry being evaluated and 2) shape literals, shapes described as WKT within the expression string. For example: 70 74 71 75 {{{ … … 77 81 }}} 78 82 83 We can use these tokens in the grammar to implement all of the MapServer supported (via GEOS) logical operators. 79 84 80 85 == Backwards Compatibility Issues ==