Understanding Programming Language Translators and Compilers

Posted on Sep 4, 2024 in Computers

A translator is a program that transforms code written in one language (source language) into another language (target language) while preserving its meaning.

Types of Translators

1. Assembler

An assembler program performs a process called assembly. This process converts a program written in assembly language into its corresponding machine-language program (without executing it).

2. Compiler

A compiler takes a program written in a higher-level language (source program) and converts it into assembly language (object program) or even directly into machine language (executable program), but it doesn’t run the program.

Functions of a Compiler:

  • Vocabulary Analysis: Recognizes the basic elements of the language and generates symbol tables. It reads each instruction and divides it into tokens, comparing them to a table of keywords.
  • Syntactic Analysis: Verifies the syntactic validity of the source instructions by recognizing the type of instruction (e.g., IF, WHILE).
  • Semantic Analysis: Determines the meaning of the instruction and generates an intermediate form if it’s executable.
  • Optimization: Minimizes the number of object program instructions or optimizes resource usage. This can be done in two stages: phase-independent optimization (on the intermediate form) and phase-dependent optimization (using machine registers).
  • Storage Allocation: Assigns addresses to all identifiers and literals.
  • Object Code Generation: Generates the final object code.

3. Interpreter

An interpreter executes each instruction and declaration of the source program as it analyzes it, without producing an object or executable program. It calls routines written in machine code to perform the operations.

4. Simulator

A simulator program allows a computer to act like another. It handles input, processing, and output as if it were the simulated computer. Unlike a translator, which works with the source program, a simulator works with the object program. Simulators can be slow and require more memory.

5. Interpreter Steps

  1. Read an instruction from the source program.
  2. Examine the instruction to determine its syntactic validity.
  3. If syntactically correct, interpret it to determine its semantics and potentially create an intermediate data structure.
  4. Execute the generated machine instructions and store partial results.
  5. If a syntax error is found, stop the process and report the error.
  6. Repeat from step 1.
  7. Translation ends when the last statement is read.

6. Precompiler (Preprocessor)

A precompiler runs before the compiler and handles code written in a different language embedded within the main source program.

7. Pseudocompiler

A pseudocompiler acts like a compiler but produces code for a virtual machine instead of a real machine.

Key Concepts

  • Grammar: Basic symbols and keywords of a language.
  • Syntax: Rules for constructing valid expressions and statements.
  • Semantics: The meaning of the code.