feat: remove redshift action in postgreSQl parser (#14)

Author: h3n4l

.gitignore

@@ -43,3 +43,5 @@ go.work.sum
 
 # node_modules
 **/node_modules/
+
+**/*.class

postgresql/PostgreSQLParser.g4

@@ -672,18 +672,7 @@ typedtableelement
    ;
 
 columnDef
-   : { $parser.Engine!=EngineRedshift }? colid typename create_generic_options? colquallist
-   | { $parser.Engine==EngineRedshift }? colid typename create_generic_options? rs_colattributes? colquallist
-   ;
-
-rs_colattributes
-   : DEFAULT b_expr
-   | IDENTITY_P OPEN_PAREN seed=iconst COMMA step=iconst CLOSE_PAREN
-   | GENERATED BY DEFAULT AS IDENTITY_P OPEN_PAREN seed=iconst COMMA step=iconst CLOSE_PAREN
-   | ENCODE StringConstant
-   | DISTKEY
-   | SORTKEY
-   | COLLATE (CASE_SENSITIVE | CASE_INSENSITIVE)
+   : colid typename create_generic_options? colquallist
    ;
 
 columnOptions

postgresql/postgresql_parser.go

@@ -6,24 +6,15 @@ import (
 	"github.com/antlr4-go/antlr/v4"
 )
 
-type Engine int
-
-const (
-	EnginePostgreSQL Engine = iota
-	EngineRedshift
-)
-
 type PostgreSQLParserBase struct {
 	*antlr.BaseParser
 
-	Engine      Engine
 	parseErrors []*PostgreSQLParseError
 }
 
 func NewPostgreSQLParserBase(input antlr.TokenStream) *PostgreSQLParserBase {
 	return &PostgreSQLParserBase{
 		BaseParser: antlr.NewBaseParser(input),
-		Engine:     EnginePostgreSQL,
 	}
 }
 

postgresql/postgresql_parser_base.go

@@ -0,0 +1,230 @@
+# Grammar-Aware Fuzzing Tool Design
+
+## Overview
+
+A fuzzing tool that generates valid SQL inputs by analyzing ANTLR v4 grammar files, ensuring comprehensive parser testing with syntactically correct queries that can stress-test parsing performance and correctness.
+
+## Goals
+
+- **Valid Input Generation**: Generate syntactically correct SQL queries based on grammar rules
+- **Performance Testing**: Create complex queries to test parser performance limits  
+- **Coverage Maximization**: Exercise all grammar rules and edge cases
+- **Automated Testing**: Integrate with CI for continuous parser validation
+
+## Architecture
+
+```
+tools/fuzzing/
+├── generator/           # Core generation logic
+│   ├── grammar_analyzer.go    # Parse ANTLR grammar files
+│   ├── rule_expander.go       # Expand grammar rules to concrete syntax
+│   └── query_builder.go       # Build SQL queries from rule expansions
+├── strategies/          # Different generation strategies
+│   ├── depth_first.go         # Generate deeply nested structures
+│   ├── breadth_first.go       # Generate wide, complex queries
+│   └── weighted.go            # Probability-based rule selection
+├── corpus/              # Generated test cases and seeds
+│   ├── seeds/                 # Hand-crafted seed inputs
+│   └── generated/             # Auto-generated test cases
+└── cmd/                 # CLI tools
+    └── fuzzer/               # Main fuzzer executable
+```
+
+## Core Components
+
+### 1. Grammar Analyzer
+
+Leverages the existing `tools/grammar/` ANTLR v4 parser to:
+- Parse target grammar files (e.g., `postgresql.g4`, `cql.g4`) 
+- Extract production rules and their alternatives
+- Build dependency graph between rules
+- Identify terminal vs non-terminal symbols
+
+```go
+type GrammarAnalyzer struct {
+    parser *grammar.ANTLRv4Parser
+    rules  map[string]*Rule
+}
+
+type Rule struct {
+    Name         string
+    Alternatives []Alternative
+    Type         RuleType // LEXER, PARSER, FRAGMENT
+}
+```
+
+### 2. Rule Expander
+
+Recursively expands grammar rules into concrete syntax trees:
+- Handles rule recursion with configurable depth limits
+- Supports probability-weighted alternative selection  
+- Manages lexer rules and literal generation
+- Tracks generation context for smart decisions
+
+```go
+type RuleExpander struct {
+    grammar    *ParsedGrammar
+    maxDepth   int
+    weights    map[string]float64
+    random     *rand.Rand
+}
+```
+
+### 3. Query Builder
+
+Converts syntax trees to executable SQL strings:
+- Handles whitespace and formatting
+- Manages identifier generation (table names, columns)
+- Ensures semantic consistency where possible
+- Outputs parseable query strings
+
+## Generation Strategies
+
+### Depth-First Strategy
+- Generates deeply nested subqueries, expressions
+- Tests parser stack limits and recursion handling
+- Focuses on structural complexity
+
+### Breadth-First Strategy  
+- Creates wide queries with many clauses, joins, columns
+- Tests parser memory usage and performance
+- Focuses on query size and breadth
+
+### Weighted Strategy
+- Uses probability weights for rule selection
+- Biases toward commonly used constructs
+- Configurable via weight files per dialect
+
+## Integration Points
+
+### With Existing Grammar Parser
+```go
+// Reuse tools/grammar/ for parsing target grammars
+analyzer := NewGrammarAnalyzer()
+targetGrammar, err := analyzer.ParseGrammarFile("postgresql/PostgreSQLLexer.g4")
+```
+
+### With Parser Testing
+```go
+// Generate test cases for specific parser
+fuzzer := NewFuzzer(postgresqlGrammar)
+queries := fuzzer.GenerateQueries(1000)
+
+for _, query := range queries {
+    // Test against postgresql parser
+    result := postgresqlParser.Parse(query)
+    // Collect metrics, detect crashes
+}
+```
+
+## Configuration
+
+### Fuzzer Config
+```yaml
+target_grammar: "postgresql"
+strategies:
+  - name: "depth_first"
+    weight: 0.3
+    max_depth: 15
+  - name: "breadth_first" 
+    weight: 0.4
+    max_width: 50
+  - name: "weighted"
+    weight: 0.3
+    weights_file: "postgresql_weights.yaml"
+
+generation:
+  count: 10000
+  max_query_length: 100000
+  seed: 42
+
+output:
+  format: "sql"
+  directory: "corpus/generated"
+```
+
+### Grammar Weights
+```yaml
+# postgresql_weights.yaml
+rules:
+  selectStmt: 0.4
+  insertStmt: 0.2  
+  updateStmt: 0.2
+  deleteStmt: 0.1
+  createStmt: 0.1
+  
+  # Bias toward complex expressions
+  expr:
+    binaryOp: 0.4
+    functionCall: 0.3
+    subquery: 0.2
+    literal: 0.1
+```
+
+## CLI Interface
+
+```bash
+# Generate queries for PostgreSQL
+./fuzzer generate --grammar postgresql --count 1000 --strategy weighted
+
+# Run continuous fuzzing with performance metrics
+./fuzzer fuzz --grammar cql --duration 1h --metrics
+
+# Validate existing corpus against parser
+./fuzzer validate --grammar postgresql --corpus corpus/postgresql/
+```
+
+## Performance Metrics
+
+### Generation Metrics
+- Queries generated per second
+- Grammar rule coverage percentage
+- Distribution of query complexity (depth, width)
+
+### Parser Testing Metrics  
+- Parse success rate
+- Average parse time per query
+- Memory usage during parsing
+- Parser crash/error detection
+
+## Implementation Phases
+
+### Phase 1: Foundation (Week 1-2)
+- Basic grammar analyzer using existing ANTLR parser
+- Simple rule expander with depth-first strategy
+- Command-line interface for manual testing
+
+### Phase 2: Core Features (Week 3-4)
+- Multiple generation strategies
+- Configuration system
+- Basic corpus management
+- Integration with existing parser tests
+
+### Phase 3: Advanced Features (Week 5-6)
+- Weighted generation with probability tuning
+- Performance metrics collection
+- CI integration for continuous fuzzing
+- Corpus minimization and deduplication
+
+### Phase 4: Optimization (Week 7-8)
+- Generation performance optimization
+- Advanced semantic awareness
+- Custom mutation strategies
+- Comprehensive documentation
+
+## Future Enhancements
+
+- **Semantic Awareness**: Generate queries with valid schema references
+- **Mutation-Based Fuzzing**: Mutate existing queries to explore edge cases
+- **Differential Testing**: Compare parser outputs across database dialects
+- **Performance Regression Detection**: Track parser performance over time
+- **Grammar Evolution**: Adapt fuzzing as grammars evolve
+
+## Dependencies
+
+- Existing `tools/grammar/` ANTLR v4 parser
+- Go standard library (`rand`, `fmt`, `strings`)
+- YAML configuration parsing
+- CLI framework (e.g., `cobra`)
+
+This design provides a solid foundation for grammar-aware fuzzing while leveraging our existing ANTLR infrastructure.