There is a proposal for openCypher to introduce syntax for path constraints specification:

• Root
• Context-free constraints in the original CIP

We are working on context-free path querying for RedisGraph which uses Cypher via libsypher.

It is necessary

• to extend libcypher to be able to use context-free (CF) constraints in Cypher
• to extend RedisGraph translator to support CF constraints
• introduce grammar normalization
• integrate with our CFPQ agorithm

Find or create utility for RDF to RedisGraph export. An analog for Neo4j.

In order to open a pool request we should do the following refactoring steps:

• Remove dev version of algebraic expression evaluation, integrate it with the original one.
• Merge path pattern traverse operation with conditional traverse operation
• Make updating of source matrices of a named path pattern more clear.
• Make a path pattern and path pattern context building more clear. Delegate the processing of algebraic expressions to the calling function.
  Also, we should provide validation of the query:
• NamedPathPredicate. Named path patterns consist of exactly one path pattern.
  Grammar:
  NamedPathPredicate = 'PATH', 'PATTERN', NamedPathName, '=', NodePattern, {(EdgePattern | PathPattern), NodePattern}, [Where]
  Supported: NamedPathPredicate = 'PATH', 'PATTERN', NamedPathName, '=', NodePattern, PathPattern, NodePattern
• PathRepetition. Only * is supported.
  Grammar: PathRepetition = PathDirection, [('*', [RangeDetail]) | '+' | '?']
  Supported: PathRepetition = PathDirection ['*']
• PathAny. We should implement it or add restrictions in the validation.
• PathNode. Properties of nodes aren't supported.
  Grammar: PathNode = '(', [NodeLabels], [Properties], ')'
  Supported: PathNode = '(', ':', LabelName, ')'
• PathGroup. Common properties of several path patterns are something strange. Maybe it is a mistake of the specification. We should check their absence.
  Grammar: PathGroup = '[', PathExpression, [Properties], ']'
  Supported: PathGroup = '[', PathExpression, ']'

CI build failed: https://circleci.com/gh/YaccConstructor/RedisGraph/5

Error:

In file included from /root/project/src/grammar/grammar.c:3:0:
/root/project/src/grammar/grammar.h:3:29: fatal error: bits/types/FILE.h: No such file or directory
 #include <bits/types/FILE.h>