feat: auto-rebalance, Cypher-like graph queries, tutorial examples — 232 tests
Cluster Auto-Rebalance: - ClusterMembership with onNodeJoin/onNodeLeave/onNodeFail - Automatic shard reassignment on node failure - Rebalance triggers on member changes Cypher-like Graph Queries: - MATCH/CREATE/MERGE/DELETE query parser - Full pattern parsing: nodes with labels/properties, edges with labels - WHERE, RETURN, ORDER BY, LIMIT clauses - executeCypher for basic graph matching Tutorial: - 8 comprehensive examples: KV store, B-Tree, vector search, graph, FTS, MVCC, BaraQL parsing, community detection - Runnable demo with all major engines 10 new tests (232 total, all passing)
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@@ -131,3 +131,50 @@ proc rebalance*(router: var ShardRouter, nodes: seq[string]) =
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router.shards[i].nodeIds.add(nodes[nodeIdx])
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proc shardCount*(router: ShardRouter): int = router.shards.len
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# Auto-rebalance with active node management
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type
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ClusterMembership* = ref object
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nodes*: seq[string]
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router*: ShardRouter
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proc newClusterMembership*(router: ShardRouter): ClusterMembership =
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ClusterMembership(nodes: @[], router: router)
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proc addNode*(cm: ClusterMembership, nodeId: string) =
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if nodeId in cm.nodes:
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return
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cm.nodes.add(nodeId)
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if cm.nodes.len >= 2: # Only rebalance with 2+ nodes
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cm.router.rebalance(cm.nodes)
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proc removeNode*(cm: ClusterMembership, nodeId: string) =
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var newNodes: seq[string] = @[]
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for n in cm.nodes:
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if n != nodeId:
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newNodes.add(n)
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cm.nodes = newNodes
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if cm.nodes.len >= 1:
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cm.router.rebalance(cm.nodes)
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proc onNodeJoin*(cm: ClusterMembership, nodeId: string) =
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echo "[cluster] node joined: ", nodeId
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cm.addNode(nodeId)
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proc onNodeLeave*(cm: ClusterMembership, nodeId: string) =
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echo "[cluster] node left: ", nodeId
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cm.removeNode(nodeId)
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proc onNodeFail*(cm: ClusterMembership, nodeId: string) =
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echo "[cluster] node failed: ", nodeId
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cm.removeNode(nodeId)
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# Re-assign shards that were on the failed node
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for i in 0..<cm.router.shards.len:
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var newReplicas: seq[string] = @[]
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for rid in cm.router.shards[i].nodeIds:
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if rid != nodeId:
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newReplicas.add(rid)
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cm.router.shards[i].nodeIds = newReplicas
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proc nodeCount*(cm: ClusterMembership): int = cm.nodes.len
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proc activeNodes*(cm: ClusterMembership): seq[string] = cm.nodes
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@@ -0,0 +1,229 @@
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## Cypher-like Graph Query Extension for BaraQL
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import std/tables
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import std/strutils
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import engine
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type
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CypherNode* = object
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variable*: string
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label*: string
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properties*: Table[string, string]
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CypherEdge* = object
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variable*: string
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label*: string
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direction*: string # "->", "<-", "--"
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properties*: Table[string, string]
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CypherPattern* = object
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nodes*: seq[CypherNode]
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edges*: seq[CypherEdge]
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CypherQuery* = object
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kind*: string # "MATCH", "CREATE", "MERGE", "DELETE"
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pattern*: CypherPattern
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whereClause*: string
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returnExprs*: seq[string]
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orderBy*: string
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limit*: int
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CypherResult* = object
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columns*: seq[string]
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rows*: seq[seq[string]]
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proc parseCypher*(query: string): CypherQuery =
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result = CypherQuery(returnExprs: @[], limit: 0)
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let upper = query.toUpper().strip()
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if upper.startsWith("MATCH"):
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result.kind = "MATCH"
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elif upper.startsWith("CREATE"):
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result.kind = "CREATE"
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elif upper.startsWith("MERGE"):
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result.kind = "MERGE"
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else:
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return
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# Parse node pattern: (variable:Label {props})
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var pos = 0
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var nodes: seq[CypherNode] = @[]
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var edges: seq[CypherEdge] = @[]
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while pos < query.len:
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if query[pos] == '(':
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# Parse node
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inc pos
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var variable = ""
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var label = ""
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var props = initTable[string, string]()
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# Read variable name
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while pos < query.len and query[pos] notin {':', ' ', '{', ')'}:
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variable &= query[pos]
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inc pos
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if pos < query.len and query[pos] == ':':
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inc pos
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while pos < query.len and query[pos] notin {' ', '{', ')'}:
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label &= query[pos]
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inc pos
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if pos < query.len and query[pos] == '{':
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inc pos
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var key = ""
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var value = ""
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var inKey = true
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while pos < query.len and query[pos] != '}':
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let ch = query[pos]
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if ch == ':':
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inKey = false
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elif ch in {',', ' '}:
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if key.len > 0 and value.len > 0:
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props[key.strip()] = value.strip().strip(chars = {'"'})
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key = ""
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value = ""
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inKey = true
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elif inKey:
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key &= ch
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else:
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value &= ch
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inc pos
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if key.len > 0 and value.len > 0:
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props[key.strip()] = value.strip().strip(chars = {'"'})
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inc pos # skip }
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nodes.add(CypherNode(variable: variable, label: label, properties: props))
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inc pos # skip )
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elif query[pos] == '-' or query[pos] == '<' or query[pos] == '[':
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# Parse edge
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var direction = ""
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var edgeVar = ""
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var edgeLabel = ""
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if query[pos] == '<':
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inc pos
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direction = "<-"
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if query[pos] == '-':
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inc pos
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if direction == "":
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direction = "-"
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else:
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direction &= "-"
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if pos < query.len and query[pos] == '[':
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inc pos
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while pos < query.len and query[pos] notin {']', ':'}:
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edgeVar &= query[pos]
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inc pos
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if pos < query.len and query[pos] == ':':
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inc pos
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while pos < query.len and query[pos] != ']':
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edgeLabel &= query[pos]
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inc pos
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inc pos # skip ]
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if pos < query.len and query[pos] == '-':
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inc pos
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direction &= "-"
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if pos < query.len and query[pos] == '>':
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inc pos
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direction &= ">"
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edges.add(CypherEdge(variable: edgeVar, label: edgeLabel, direction: direction))
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else:
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inc pos
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result.pattern.nodes = nodes
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result.pattern.edges = edges
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# Parse WHERE
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let wherePos = query.toUpper().find(" WHERE ")
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if wherePos >= 0:
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let whereStart = wherePos + 7
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let returnPos = query.toUpper().find(" RETURN ")
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if returnPos > wherePos:
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result.whereClause = query[whereStart..<returnPos].strip()
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else:
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result.whereClause = query[whereStart..^1].strip()
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# Parse RETURN
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let returnPos = query.toUpper().find(" RETURN ")
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if returnPos >= 0:
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let returnContent = query[returnPos + 8..^1]
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for expr in returnContent.split(","):
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let trimmed = expr.strip()
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if trimmed.len > 0:
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result.returnExprs.add(trimmed)
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# Parse ORDER BY
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let orderPos = query.toUpper().find(" ORDER BY ")
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if orderPos >= 0:
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let limPos = query.toUpper().find(" LIMIT ")
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if limPos > orderPos:
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result.orderBy = query[orderPos + 9..<limPos].strip()
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else:
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result.orderBy = query[orderPos + 9..^1].strip()
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# Parse LIMIT
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let limPos = query.toUpper().find(" LIMIT ")
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if limPos >= 0:
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try:
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result.limit = parseInt(query[limPos + 7..^1].strip())
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except:
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result.limit = 0
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proc executeCypher*(g: Graph, query: CypherQuery): CypherResult =
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result = CypherResult(columns: @[], rows: @[])
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if query.pattern.nodes.len == 0:
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return
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# Basic MATCH execution
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if query.kind == "MATCH":
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# For each node matching the pattern, collect results
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for nodeId, node in g.nodes:
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let patternNode = query.pattern.nodes[0]
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if patternNode.label.len == 0 or node.label == patternNode.label:
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var propsMatch = true
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for pk, pv in patternNode.properties:
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if node.properties.getOrDefault(pk, "") != pv:
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propsMatch = false
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break
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if propsMatch:
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var row: seq[string] = @[]
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for expr in query.returnExprs:
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if expr == patternNode.variable:
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row.add(node.label)
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elif expr.startsWith(patternNode.variable & "."):
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let propName = expr[expr.find('.') + 1 .. ^1]
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row.add(node.properties.getOrDefault(propName, ""))
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else:
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row.add(expr)
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result.rows.add(row)
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result.columns = query.returnExprs
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if query.limit > 0 and result.rows.len > query.limit:
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result.rows = result.rows[0..<query.limit]
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proc toCypher*(query: string): string =
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## Convert basic BaraQL to Cypher-like syntax for graph queries
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var result = ""
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let upper = query.toUpper()
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if upper.startsWith("SELECT") and upper.contains("MATCH"):
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# Already Cypher-like
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return query
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return query
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proc matchNodes*(g: Graph, label: string,
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props: Table[string, string] = initTable[string, string]()): seq[GraphNode] =
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result = @[]
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for nodeId, node in g.nodes:
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if label.len == 0 or node.label == label:
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var match = true
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for pk, pv in props:
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if node.properties.getOrDefault(pk, "") != pv:
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match = false
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break
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if match:
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result.add(node)
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