A grammar describes the syntax of a programming language, and might be defined in Backus-Naur form (BNF). A lexer performs lexical analysis, turning text into tokens. A parser takes tokens and builds a data structure like an abstract syntax tree (AST). The parser is concerned with context: does the sequence of tokens fit the grammar? A compiler is a combined lexer and parser, built for a specific grammar.
C++ Insights - See your source code with the eyes of a compiler
Library to parse and work with the C++ AST
C++ Mathematical Expression Parsing And Evaluation Library https://www.partow.net/programming/exprtk/index.html
A library to parse C/C++ source as AST
libpypa is a Python parser implemented in pure C++
A language and compiler for irregular tensor programs.
Peter's Amazing Syntax Tree Analyzer
Toy compiler
JavaScript AST in C++
parser combinator and AST generator in c++17
C++17 implementation of an AST for Verilog code generation
AST2DB is a powerful tool that utilizes clang to parse C/C++ source code, extract Abstract Syntax Tree (AST) information, and store it in an SQLite database.