The Answer:

Introduction:
In computer programming, a parser is a software component that takes input in the form of a sequence of tokens and builds a data structure (such as a parse tree or an abstract syntax tree). The parser analyzes the syntactic structure of the code and verifies whether it conforms to the grammar rules of the programming language.

The Expectation:
The statement "Parsers are expected to parse the whole code" is true. Parsers are designed to analyze and process the entire code provided to them.

Explanation:
When a parser is given a piece of code to parse, it starts by breaking down the code into a series of tokens. Tokens are the smallest units of a programming language, such as keywords, identifiers, operators, and literals. The parser then analyzes the syntax of these tokens to determine the structure and correctness of the code.

1. Syntax Analysis:
The primary task of a parser is to perform syntax analysis, also known as parsing. Syntax analysis involves checking whether the sequence of tokens conforms to the grammar rules of the programming language. The parser ensures that the code is free from syntax errors and constructs a parse tree or an abstract syntax tree (AST) representing the syntactic structure of the code.

2. Error Detection:
During the parsing process, the parser can detect various types of errors, such as missing or misplaced punctuation, incorrect use of operators, and violations of language-specific rules. By identifying these errors, the parser helps programmers debug their code and fix any syntactic issues.

3. Identification of Language Constructs:
Parsers are responsible for identifying and extracting the different language constructs present in the code. These constructs include variables, functions, classes, control flow statements, and other language-specific elements. By parsing the entire code, the parser builds a comprehensive understanding of the program's structure and components.

Conclusion:
In conclusion, parsers are expected to parse the whole code provided to them. They perform syntax analysis, detect errors, and identify language constructs within the code. By parsing the entire code, parsers ensure that the program adheres to the language's grammar rules and can provide valuable insights and feedback to programmers.