![non-recursive parser Components
• This non-recursive parser looks up which product to be applied in a
parsing table. A LL(1) parser has the following components:
• (1) buffer: an input buffer which contains the string to be passed
• (2) stack: a pushdown stack which contains a sequence of grammar symbols
• (3) A parsing table: a 2d array M[A, a]
• where
• A->non-terminal, a->terminal or $
• (4) output stream:
• end of the stack and an end of the input symbols are both denoted with $](https://image.slidesharecdn.com/non-recursivepredictiveparsing-230424214229-79cd9bf2/85/Non-Recursive-Predictive-Parsing-pptx-3-320.jpg)
![Algorithm for non recursive Predictive Parsing:
• The main Concept ->With the help of FIRST() and FOLLOW() sets, this
parsing can be done using just a stack that avoids the recursive calls.
• For each rule, A->x in grammar G:
• For each terminal ‘a’ contained in FIRST(A) add A->x to M[A, a] in the parsing
table if x derives ‘a’ as the first symbol.
• If FIRST(A) contains null production for each terminal ‘b’ in FOLLOW(A), add
this production (A->null) to M[A, b] in the parsing table.](https://image.slidesharecdn.com/non-recursivepredictiveparsing-230424214229-79cd9bf2/85/Non-Recursive-Predictive-Parsing-pptx-4-320.jpg)
Non- Recursive Predictive Parsing.pptx
- 1. Non- Recursive Predictive Parsing
- 2. Non- Recursive Predictive Parsing • Non-Recursive predictive parsing uses a parsing table that shows which production rule to select from several alternatives available for expanding a given non-terminal and the first terminal symbol that should be produced by that non-terminal. • The parsing table consists of rows and columns where there are row for each non-terminal and a column for each terminal symbol including S, the end marker for the input string.
- 3. non-recursive parser Components • This non-recursive parser looks up which product to be applied in a parsing table. A LL(1) parser has the following components: • (1) buffer: an input buffer which contains the string to be passed • (2) stack: a pushdown stack which contains a sequence of grammar symbols • (3) A parsing table: a 2d array M[A, a] • where • A->non-terminal, a->terminal or $ • (4) output stream: • end of the stack and an end of the input symbols are both denoted with $
- 4. Algorithm for non recursive Predictive Parsing: • The main Concept ->With the help of FIRST() and FOLLOW() sets, this parsing can be done using just a stack that avoids the recursive calls. • For each rule, A->x in grammar G: • For each terminal ‘a’ contained in FIRST(A) add A->x to M[A, a] in the parsing table if x derives ‘a’ as the first symbol. • If FIRST(A) contains null production for each terminal ‘b’ in FOLLOW(A), add this production (A->null) to M[A, b] in the parsing table.
- 5. LR Parser
- 6. LR Parser • LR parsing is one type of bottom up parsing. It is used to parse the large class of grammars. • In the LR parsing, "L" stands for left-to-right scanning of the input. • "R" stands for constructing a right most derivation in reverse. • "K" is the number of input symbols of the look ahead used to make number of parsing decision.
- 7. Types of LR Parser • LR parsing is divided into four parts: LR (0) parsing, SLR parsing, CLR parsing and LALR parsing.
- 8. LR algorithm • The LR algorithm requires stack, input, output and parsing table. In all type of LR parsing, input, output and stack are same but parsing table is different.
- 9. • Input buffer is used to indicate end of input and it contains the string to be parsed followed by a $ Symbol. • A stack is used to contain a sequence of grammar symbols with a $ at the bottom of the stack. • Parsing table is a two dimensional array. It contains two parts: Action part and Go To part.