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A compiler -- in general, a language processor -- is a program that takes as input a program written in the source language and translates it into another (the target language), typically (although not necessarily) one understandable by a machine.

There are various types of language processors: translators (between two high-level languages), compilers (from a high-level language to a low-level language), decompilers (from low- to high-level languages), rewriters (within the same language).

Modern compilers usually take source code and produce object code, in a form usable by other programs, such as a linker or a virtual machine. Examples:

• C/C++ source code is typically compiled to object code for later linking (.o files);
• Java is typically compiled (Sun compiler) to binary class files (.class), used by the virtual machine. The GCC Java compiler can, besides the class files, also produce object files (like for C/C++).

Compiler or interpreter? Although both types of language analysis tools share some properties, they differ in how they handle the analyzed code. Compilers produce an equivalent version of the original language in a target language; interpreters translate the input language, not into a target version, but rather directly into the execution of the actions described in the source language.

The following sections cover the overall development process and contain both theoretical and practical aspects.

• Introdução ao Desenvolvimento de Compiladores - establishes the basic framework for the other sections
• Theoretical Aspects of Lexical Analysis - presents the basic principles behind lexical analysis and how to build lexical analysers
• The Flex Lexical Analyzer - presents a concrete lexical analysis tool: flex
• Introduction to Syntax - presents a basic introduction to grammar formalisms and basic concepts needed for understanding parsing
• Top-Down Parsing - presents top-down parsing techniques; special emphasis is put on LL(1) parsers
• Attribute Grammars - presents the concepts supporting the communication between syntax and semantics
• The YACC Parser Generator - presents the YACC parser and parser generator (byacc, bison, etc.)
• Bottom-Up Parsing - presents bottom-up parsing, the LR family
• Semantic Analysis - presents the basic concepts behind semantic analysis: symbols, symbol tables, etc.
• Code Generation - presents the code generation support
• Optimization Topics - presents a few topics concerning optimization