c-scripting/examples/expression_parser.h

#ifndef EXPRESSION_PARSER_H
#define EXPRESSION_PARSER_H

////////////////////////////////
// Operators

//// PRECEDENCE ////

typedef struct EXP_Precedence{
  String8 name;
  U32 order;
  B32 right_to_left;
} EXP_Precedence;

#define SYMBOL_SET_DEFINE EXP_PRECEDENCE
#define EXP_PRECEDENCE_Type    EXP_Precedence
#define EXP_PRECEDENCE_elf_section    ".sy.precedence"
#define EXP_PRECEDENCE_coff_a_section ".sy$precedence_a"
#define EXP_PRECEDENCE_coff_m_section ".sy$precedence_m"
#define EXP_PRECEDENCE_coff_z_section ".sy$precedence_z"
#define EXP_PRECEDENCE_marker  precedence
#include "symbol_set.define.h"

#define EXP_PRECEDENCE(ord,N,...) \
SyDefine(EXP_PRECEDENCE, N) = { .order = (ord), .name = str8_const(#N), __VA_ARGS__ }

//// OPERATOR ////

typedef struct EXP_Operator{
  String8 name;
  String8 token_str;
  SY__UAddr precedence_id;
} EXP_Operator;

#define SYMBOL_SET_DEFINE EXP_OPERATOR
#define EXP_OPERATOR_Type    EXP_Operator
#define EXP_OPERATOR_elf_section    ".sy.operator"
#define EXP_OPERATOR_coff_a_section ".sy$operator_a"
#define EXP_OPERATOR_coff_m_section ".sy$operator_m"
#define EXP_OPERATOR_coff_z_section ".sy$operator_z"
#define EXP_OPERATOR_marker  operator
#include "symbol_set.define.h"

#define EXP_OPERATOR(N,str,P) \
SyDefine(EXP_OPERATOR, N) = { .name = str8_const(#N), \
.token_str = str8_const(str), \
.precedence_id = SyRaw(EXP_PRECEDENCE, P) }

#if SY__MAIN
SY_INIT(EXP_OPERATOR){
  for (SyEach(EXP_OPERATOR, op)){
    op->precedence_id = SyIDFromRaw(EXP_PRECEDENCE, op->precedence_id);
  }
}
#endif

////////////////////////////////
// Operator Functions

static U32 exp_operator_id_from_string(String8 string);

////////////////////////////////
// Lexer Types

#define EXP_TokenKindXList(X) \
X(Error)\
X(EndOfFile)\
X(Whitespace)\
X(IDNum)\
X(Operator)\
X(OpenParen)\
X(CloseParen)\
X(OpenBracket)\
X(CloseBracket)\
X(OpenBrace)\
X(CloseBrace)

typedef enum EXP_TokenKind{
#define X(N) EXP_TokenKind_##N,
  EXP_TokenKindXList(X)
#undef X
  EXP_TokenKind_COUNT
} EXP_TokenKind;

typedef struct EXP_Token{
  EXP_TokenKind kind;
  U32 pos;
} EXP_Token;

typedef struct EXP_TokenArray{
  EXP_Token *tokens;
  U64 count;
} EXP_TokenArray;

////////////////////////////////
// Lexer Functions

static EXP_TokenArray exp_lex(Arena *arena, String8 text);

////////////////////////////////
// Parser Types

#define EXP_ParseNodeKindXList(X)\
X(NULL)\
X(Operator)\
X(Leaf)

typedef enum EXP_ParseNodeKind{
#define X(N) EXP_ParseNodeKind_##N,
  EXP_ParseNodeKindXList(X)
#undef X
  EXP_ParseNodeKind_COUNT
} EXP_ParseNodeKind;

typedef struct EXP_ParseNode{
  EXP_ParseNodeKind kind;
  union{
    struct{
      U32 operator_id;
      struct EXP_ParseNode *child[2];
    } op;
    struct{
      U32 token_idx;
    } leaf;
  };
} EXP_ParseNode;

typedef struct EXP_ParseCtx{
  String8 text;
  EXP_TokenArray tokens;
  EXP_Token *token;
  B32 error;
  U32 error_token_idx;
  String8 error_message;
} EXP_ParseCtx;

typedef struct EXP_OperatorRead{
  U32 operator_id;
  U32 precedence_level;
  B32 right_to_left;
} EXP_OperatorRead;

////////////////////////////////
// Parser Functions

static EXP_ParseNode* exp_parse(Arena *arena, String8 text, EXP_TokenArray tokens);

static EXP_ParseNode* exp__parse_op_rec(Arena *arena, EXP_ParseCtx *ctx,
                                        EXP_ParseNode *left, U32 precedence_level);
static EXP_ParseNode* exp__parse_op(Arena *arena, EXP_ParseCtx *ctx);
static EXP_ParseNode* exp__parse_leaf(Arena *arena, EXP_ParseCtx *ctx);

static void           exp__parse_errorf(Arena *arena, EXP_ParseCtx *ctx, char *fmt, ...);
static void           exp__parse_skip_whitespace(EXP_ParseCtx *ctx);
static EXP_OperatorRead exp__parse_read_operator(EXP_ParseCtx *ctx);

static void exp_parse_node_print(String8 text, EXP_TokenArray tokens,
                                 EXP_ParseNode *node, S32 indent);

#endif //EXPRESSION_PARSER_H