Phases of compiler

A Compiler is a language processor that:

• translates a program from source language to target language,
• reports errors if any,
• generates executable machine code.

Lexical Analyzer

• Lexical analysis is also called linear analysis or scanning
• It processes character from left to right & group the character stream into significant unit called lexemes
• These lexemes are mapped into token
• It also does the additional job of removing extra whitespace, comments added by the user, etc. from the program

Syntax Analyzer

• The syntax analysis phase takes word/tokens from the lexical analyzer and checks the syntactic correctness of the input program
• Syntax analysis identifies and notifies the syntactic errors in the program once the program has been broken into the tokens
• It often referred as hierarchical analysis or simply parsing
• The hierarchical structure of the source program can be represented by a parse tree

Semantic Analyzer

• Once the program is syntactically correct means grammatically correct the next task is to check semantic correctness
• This phase performs the checks on the meaning of the statement and makes the necessary modification in the parse tree representation
• The word semantic refer to meaning & the semantic analyzer checks the meaning of the program
• This phase checks the source program for semantic error and gathers “type information” about the program element