Overview
LL(1) table construction maps a nonterminal and lookahead token to one production when the grammar is predictive.
CoreSource checked
LL(1) Parse Table Construction
Builds a predictive parsing table from FIRST and FOLLOW sets.
Quick Facts
Compact metadata for implementation and discovery.
- Category
- Parsing
- Difficulty
- Intermediate
- Family
- Predictive Parsing
- Tier
- Core
- Status
- Verified
- Review
- Source Checked
- Sources
- 1
- Formulas
- 1
- Relationships
- 2
- Code example
- Ready
- Visualization
- Ready
Core Concepts
lookahead tokenfirst setfollow setpredictive table
Quick facts
Complexity
Runtime and memory behavior at a glance.
Best
O(grammar size)
Average
O(grammar size)
Worst
O(grammar size)
Space
O(nonterminals * terminals)
When to Use
- Use when language parsing needs lookahead token.
- Use when the input matches the assumptions behind predictive Parsing.
When Not to Use
- Avoid when the grammar class does not match the parser's assumptions.
- Avoid when a simpler algorithm gives the required result with less setup.
What It Does
- Builds a predictive parsing table from FIRST and FOLLOW sets
- Uses lookahead token and first set to guide the work.
- Produces parse tree.
Use Cases
- Language parsing
- Compiler front ends
- Structured text processing
Inputs
- Tokens or grammar
- Parser state
Outputs
- Parse tree
- Automaton
- Grammar table or parse result
Key Formulas (1)
Table entry
table[A, token] = production A → α when token in FIRST(α)
table[A, token] = production A -> alpha when token in FIRST(alpha)Selects the production for a nonterminal and lookahead token.
Pseudocode
- 1.Prepare tokens, grammar rules, tables, or automaton states
- 2.Advance through tokens or grammar items according to the parsing rule
- 3.Create parse nodes, state transitions, or table entries when a rule applies
- 4.Report an error or return the completed structure
Canonical Example
- Input
- tokens = ['id', '+', 'id', '*', 'id'] with a tiny grammar or precedence table
- Output
- parse tree, automaton, item sets, or syntax-directed state
- Explanation
- The parser or automaton construction applies grammar rules to recover structure from the token stream.
Implementation Notes
- Report errors with token position and expected grammar symbols.
- Keep the lookahead token step separate enough to test independently.
- Keep lexical analysis separate from parsing unless the method explicitly combines them.
Common Pitfalls
- Ambiguity and left recursion must be handled according to the parser type.
- Test edge cases, not only clean examples.
- Mixing token positions, character offsets, and grammar states can produce misleading parse errors.
Interactive Mechanism Walkthrough
Sequence Window & Automaton AlignmentShow grammar items, parser states, and consumed input as parsing progresses.
Input:ABABABCABAB
Window:ABAB
Step 1 of 4: Prepare tokens, grammar rules, tables, or automaton states
parsing-mechanismNotes
LL(1) Parse Table Construction should be used with the assumptions and tradeoffs of predictive Parsing in mind.
Sources (1)
What each reference supports for this entry.
Compilers: Principles, Techniques, and Tools
BookCompiler textbook support for LL(1) Parse Table Construction's grammar analysis, parser construction, and implementation constraints.
Explore Next
Good next jumps from the relationship graph, ranked for useful discovery.
Relationships
View full relationship pageLL(1) parse tables are built from FIRST and FOLLOW set information.
Related Algorithms
Tags
ParsingTop-Down ParsingGrammar AnalysisParser Generator