P-Language Compiler

A complete compiler for the P language (a Pascal-like teaching language), built end to end: lexer → parser → AST → semantic analyzer → RISC-V code generation. The generated assembly runs on a real RISC-V target.

 .p source
    │  scanner.l  (lex/flex)              — tokenize
    ▼
 tokens
    │  parser.y   (yacc/bison)            — parse to a grammar
    ▼
 parse
    │  include/AST + lib/AST  (Visitor)   — build the AST
    ▼
 AST
    │  lib/sema/SemanticAnalyzer.cpp      — scope & type checking (symbol table)
    ▼
 checked AST
    │  lib/codegen/CodeGenerator.cpp      — emit RISC-V assembly
    ▼
 RISC-V .S

Pipeline

Stage	Implementation	What it does
Lexical analysis	src/scanner.l (235 lines)	flex scanner: tokens, keywords, literals, comments
Syntactic analysis	src/parser.y (798 lines)	bison grammar for the full P language
AST	src/include/AST/ + src/lib/AST/ (17 node types)	Visitor-pattern AST built during parsing
Semantic analysis	src/lib/sema/SemanticAnalyzer.cpp (739 lines)	scoped symbol table, type checking, error reporting
Code generation	src/lib/codegen/CodeGenerator.cpp (541 lines)	emits RISC-V assembly from the checked AST

The AST uses the visitor pattern (AstNodeVisitor): the semantic analyzer and code generator are both visitors that walk the same tree, so each stage is decoupled from the node definitions.

Highlights

• Full front-to-back pipeline — from source text all the way to working RISC-V assembly, passing the course's basic, advance, and bonus test suites (see test/).
• Symbol table with scope management handles nested functions, local vs. global variables, and parameter binding for both type checking and stack-frame layout during codegen.
• RISC-V backend manages register/stack allocation, control flow (if/while/for with generated branch labels), function calls, and I/O.

Build & Run

The project targets a RISC-V toolchain and is built inside the course Docker image:

cd src && make           # builds the `compiler` binary (flex + bison + g++)
./compiler <input.p> --save-path <output_dir>   # emits RISC-V assembly

# or run the test suite
cd test && make

Per-phase design write-ups are in docs/ (phase1_lexical … phase5_codegen).

Context

Coursework for Introduction to Compiler Design at NYCU (Fall 2023), taught by Prof. Yi-Ping You; developed incrementally across five assignments and consolidated here as one project. The lex/yacc scaffolding and test harness were course-provided; the scanner rules, grammar, AST classes, semantic analyzer, and code generator are my own. Cleaned up (generated scanner.c/parser.cpp, build artifacts, and executables removed) and documented for release.