defs.h

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

// Structure and enum definitions
// Copyright (c) 2019 Warren Toomey, GPL3

#define TEXTLEN 512    // Length of symbols in input
#define NSYMBOLS 1024  // Number of symbol table entries

// Token types
enum {
    T_EOF,
    // Binary operators
    T_PLUS,
    T_MINUS,
    T_STAR,
    T_SLASH,
    T_EQ,
    T_NE,
    T_LT,
    T_GT,
    T_LE,
    T_GE,
    // Assignment operators
    T_INTLIT,
    T_SEMI,
    T_ASSIGN,
    T_IDENT,
    // Keywords
    T_PRINT,
    T_INT
};

// Token structure
struct token {
    int token;     // Token type, from the enum list above
    int intvalue;  // For T_INTLIT, the integer value
};

// AST node types
enum {
    A_ADD = 1,
    A_SUBTRACT,
    A_MULTIPLY,
    A_DIVIDE,
    A_EQ,
    A_NE,
    A_LT,
    A_GT,
    A_LE,
    A_GE,
    A_INTLIT,
    A_IDENT,
    A_LVIDENT,
    A_ASSIGN
};

// Abstract Syntax Tree structure
struct ASTnode {
    int op;                // "Operation" to be performed on this tree
    struct ASTnode* left;  // Left and right child trees
    struct ASTnode* right;
    union {
        int intvalue;  // For A_INTLIT, the integer value
        int id;        // For A_IDENT, the symbol slot number
    } v;
};

// Symbol table structure
struct symtable {
    char* name;  // Name of a symbol
};