The module of API interface provides functions for
external. The Word Breaker (Tokenizer) and Analyzer (Parser)
in the compiler check the syntax of the SQL sentence, and put
the sentence into the hierarchical data structures —syntax tree,
which is facilitate for following parts. The Code Generator
produces a type of assembly code for SQLite according to the
syntax tree, and the Virtual Machine implements the code.
Virtual Machine is mainly an abstract computing engine
designed for the operation of the database. The Back Part
includes the B-tree, page cache, and the operating system
interfaces. B-tree is mainly to support the index, maintain the
complex relationship between the various pages, and find the
required data easily and quickly. The main role of the page
cache is to transfer pages between B-tree and the hard disk
through the operating system interface.