Chapter 2 : Syntax Analyzer

Introduction of Syntax analyzer, Introduction of ambiguity in Compiler Design

16 February, 2016     

• This chapter is devoted to parsing methods that are typically used in compilers.
  
• The syntax of programming language constructs can be specified by CFG (Context free grammar)or BNF(Backus- Naur form) Notations.
  
• A grammar gives a precise , yet easy -to - understand, syntactic specification of a programming language.
  
• We have learnt how tokens generate in Lexical analyzer step.
• In this step, we will learn how can we create a parse tree.
•   Through parse tree a complier can understand the structure of program. how it will pass the string etc.
• Parsing can be done by two methods and these two methods also have sub parts .
• So start leaning now What is Syntax Analyzer?

• In Top down Parsing , It will start from starting symbol and proceed to children.
  
• In Bottom up parsing, it will start from children and will proceed to start symbol.
  
• Its more powerful approach.
  
• In TDP , it used Left recursion while deriving the string.
• In TDP , when a variable contain more than one possibility it become difficult to choose the right production.
• Derive a string with more than two parser called Ambiguous grammar.
• Types of Top down parser:

1. Recursive Decent parser(Backtracking)
2. Non- recursive parser(LL(1))(No recursion) (Predictive Parsing)

Bottom Up parser divide into two parts(Shift Reduce parser) :

Sometimes an ambiguous can be written to eliminate the ambiguity.