gudusoft.gsqlparser.resolver2.model

Class FromScopeIndex

Object

gudusoft.gsqlparser.resolver2.model.FromScopeIndex

public class FromScopeIndex
extends Object

Index structure for fast lookups in FromScope.

This class optimizes O(N) linear scans to O(1) hash lookups for common operations like finding tables by alias/name and finding candidate namespaces for star column inference.

The index is built lazily on first access and cached for subsequent lookups. This avoids the overhead of building the index when it's not needed.

Performance improvement: For queries with N tables and M column references, reduces complexity from O(N*M) to O(N + M).

Slice S2 — vendor-aware identifier compares. Pre-S2 keys were built via raw String.toLowerCase() which broke quoted-sensitive dialects (Oracle / Postgres / Snowflake / Hive / Teradata quoted) and BigQuery's case-sensitive table rule. S2 stores aliases / display names raw (preserving quotes and original case) and routes lookups through IdentifierService via the supplied INameMatcher with ESQLDataObjectType.dotTable. The exact-text fast probe still handles same-as-written queries in O(1); cross-case / quoted-vs- unquoted lookups fall through to a vendor-aware linear scan. Storing the raw form is critical: a normalized key would lose quote provenance — codex round-1 review caught that comparing the stripped-and-folded stored key against the raw input would false-positive an unquoted probe against a quoted alias on strict-case dialects.

Since:

3.1.0.9

Constructor Summary

Constructors

Constructor and Description
FromScopeIndex(List<ScopeChild> children) Creates an index from the given list of scope children using a vendor-agnostic DefaultNameMatcher.
FromScopeIndex(List<ScopeChild> children, INameMatcher nameMatcher) Creates an index from the given list of scope children, using the supplied matcher to normalize alias / table-name keys per-vendor.

Method Summary

Modifier and Type	Method and Description
ScopeChild	findByAlias(String alias) Finds a ScopeChild by its alias (vendor-aware).
ScopeChild	findByQualifier(String qualifier) Finds a ScopeChild by alias first, then by namespace name (vendor-aware).
INamespace	findCandidateNamespace(String tablePrefix) Finds a candidate namespace for column resolution.
TTable	findTableByQualifier(String qualifier) Gets the TTable from a ScopeChild by qualifier, if the namespace represents a table.
static FromScopeIndex	fromScope(IScope scope) Creates an index from a scope, extracting the FromScope if needed.
int	getChildCount() Gets the total number of children indexed.
INamespace	getPreferredStarNamespace() Gets the first namespace that supports star columns or dynamic inference.
boolean	isEmpty() Checks if the index is empty.
String	toString()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

FromScopeIndex

public FromScopeIndex(List<ScopeChild> children)

Creates an index from the given list of scope children using a vendor-agnostic DefaultNameMatcher. Prefer the matcher-aware constructor; this overload exists for synthetic / unit-test scopes that have no GlobalScope above them.

Parameters:

children - The list of ScopeChild from a FromScope

FromScopeIndex

public FromScopeIndex(List<ScopeChild> children,
                      INameMatcher nameMatcher)

Creates an index from the given list of scope children, using the supplied matcher to normalize alias / table-name keys per-vendor.

Parameters:

children - The list of ScopeChild from a FromScope

nameMatcher - Vendor-aware matcher (typically the GlobalScope's)

Method Detail

findByAlias

public ScopeChild findByAlias(String alias)

Finds a ScopeChild by its alias (vendor-aware).

Parameters:

alias - The alias to search for

Returns:

The matching ScopeChild, or null if not found

findByQualifier

public ScopeChild findByQualifier(String qualifier)

Finds a ScopeChild by alias first, then by namespace name (vendor-aware).

Parameters:

qualifier - The qualifier (alias or table name) to search for

Returns:

The matching ScopeChild, or null if not found

findTableByQualifier

public TTable findTableByQualifier(String qualifier)

Gets the TTable from a ScopeChild by qualifier, if the namespace represents a table.

Parameters:

qualifier - The qualifier (alias or table name) to search for

Returns:

The TTable if found and the namespace is a table, null otherwise

getPreferredStarNamespace

public INamespace getPreferredStarNamespace()

Gets the first namespace that supports star columns or dynamic inference. Used for resolving unqualified column references.

Returns:

The preferred star namespace, or null if none exists

findCandidateNamespace

public INamespace findCandidateNamespace(String tablePrefix)

Finds a candidate namespace for column resolution.

If a table prefix is provided, looks up by that prefix. Otherwise, returns the first star/dynamic namespace for unqualified columns.

Parameters:

tablePrefix - The table prefix (alias or name), or null for unqualified columns

Returns:

The candidate namespace, or null if not found

getChildCount

public int getChildCount()

Gets the total number of children indexed.

Returns:

The child count

isEmpty

public boolean isEmpty()

Checks if the index is empty.

Returns:

true if no children are indexed

fromScope

public static FromScopeIndex fromScope(IScope scope)

Creates an index from a scope, extracting the FromScope if needed. Walks the scope chain to find the GlobalScope's name matcher so vendor-specific identifier rules apply (S2).

Parameters:

scope - The scope (SelectScope, UpdateScope, or FromScope)

Returns:

A new FromScopeIndex, or null if no FromScope is found

toString

public String toString()

Overrides:

toString in class Object