rule_macros.h File Reference

DSL macros for defining grammar production rules. More...

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Macros
#define	PREFIX_TK(tk)   TK_ ## tk
	See Name Mapping for Identifiers
#define	PREFIX_NT(nt)   NT_ ## nt
	See Name Mapping for Identifiers
#define	POSTFIX_NT_REST(nt)   nt ## _REST
	See Name Mapping for Identifiers
#define	EOA   -1
	Sentinel for end of alternative.
#define	EOP   -2
	Sentinel for end of production body.
#define	TK(tk)   { .ty = RDESC_TOKEN, .id = PREFIX_TK(tk) }
	Macro to create a terminal (token) production symbol.
#define	NT(nt)   { .ty = RDESC_NONTERMINAL, .id = PREFIX_NT(nt) }
	Macro to create a nonterminal production symbol.
#define	EPSILON   SEOA
	Epsilon production (empty/null production). Use to represent an empty alternative that matches nothing. This is equivalent to ε in BNF notation.
#define	r(...)   { { __VA_ARGS__, SEOA }, SEOP }
	Macro to define a grammar rule. Adds end of alternative and end of production body sentinels to grammar rules.
#define	ropt(...)    r(__VA_ARGS__ alt EPSILON)
	Macro to define an optional grammar rule (epsilon production).
#define	rrr(head, base, suffix)
	Defines right-recursive list rules. base and suffix parameters should wrapped with parenthesis (()).
#define	alt   , SEOA, }, {
	Separates grammar alternatives (alternative separator).

Detailed Description

DSL macros for defining grammar production rules.

Provides macros to define production rules in a more readable way.

Name Mapping for Identifiers

POSTFIX_NT_REST, PREFIX_TK, and PREFIX_NT macros determine how a raw token name passed to TK(X)/NT(X) is expanded into a C identifier (typically an enum member).

• Default: Identity mapping. PREFIX_TK(ID) expands to TK_ID, POSTFIX_NT(ID) to NT_ID, and POSTFIX_NT_REST(ID) to ID_REST.
• Override: Define this macro before including rule_macros.h to add namespaces (e.g., #define PREFIX_TK(x) MY_TK_ ## x).

Definition in file rule_macros.h.

Macro Definition Documentation

alt

#define alt   , SEOA, }, {

Separates grammar alternatives (alternative separator).

Expands to end-of-body sentinel and new alternative initialization.

Use between alternatives. For example, r(α alt β alt γ) is equivalent to α / β / γ, where / is ordered choice operator.

Definition at line 133 of file rule_macros.h.

EOA

#define EOA   -1

Sentinel for end of alternative.

Definition at line 44 of file rule_macros.h.

EOP

#define EOP   -2

Sentinel for end of production body.

Definition at line 46 of file rule_macros.h.

EPSILON

#define EPSILON   SEOA

Epsilon production (empty/null production). Use to represent an empty alternative that matches nothing. This is equivalent to ε in BNF notation.

Definition at line 65 of file rule_macros.h.

NT

#define NT

(

nt

)

{ .ty = RDESC_NONTERMINAL, .id = PREFIX_NT(nt) }

Macro to create a nonterminal production symbol.

Definition at line 58 of file rule_macros.h.

POSTFIX_NT_REST

#define POSTFIX_NT_REST

(

nt

)

nt ## _REST

See Name Mapping for Identifiers

Definition at line 40 of file rule_macros.h.

PREFIX_NT

#define PREFIX_NT

(

nt

)

NT_ ## nt

See Name Mapping for Identifiers

Definition at line 35 of file rule_macros.h.

PREFIX_TK

#define PREFIX_TK

(

tk

)

TK_ ## tk

See Name Mapping for Identifiers

Definition at line 30 of file rule_macros.h.

r

#define r

(

...

)

{ { __VA_ARGS__, SEOA }, SEOP }

Macro to define a grammar rule. Adds end of alternative and end of production body sentinels to grammar rules.

Definition at line 72 of file rule_macros.h.

ropt

#define ropt

(

...

)

r(__VA_ARGS__ alt EPSILON)

Macro to define an optional grammar rule (epsilon production).

This is a shortcut for a rule with two alternative: an alternative with the symbols provided and an empty (epsilon) one.

ropt(A, α) is equivalent to:

A → α / ε

For example, ropt(STMT, STMTS) defines:

<stmts> ::= <stmt> <stmts>
          / E

Definition at line 91 of file rule_macros.h.

rrr

#define rrr	(		head,
			base,
			suffix
	)

Value:

        r(_rdesc_priv_trim_paren base, NT(POSTFIX_NT_REST(head))), \
        ropt(_rdesc_priv_trim_paren suffix, NT(POSTFIX_NT_REST(head)))

Defines right-recursive list rules. base and suffix parameters should wrapped with parenthesis (()).

Defines two nonterminals: the list head and its rest continuation. rrr(A, (β), (α)) is equivalent to:

A  → β A'
A' → α A' / ε

For example, rrr(EXPR_LS, (NT(EXPR)), (TK(COMMA), NT(EXPR))) defines:

1. <expr_ls> ::= <expr> <expr_ls_rest>
2. <expr_ls_rest> ::= "," <expr> <expr_ls_rest>
                    / E

Warning

rrr(X, ...) expands into two production rules defining nonterminals NT_X and NT_X_REST. You must explicitly define NT_X_REST right after NT_X in your nonterminal enum definition. See Name Mapping for Identifiers.

Parameters

head	The base nonterminal.
base	The initial production sequence (beta).
suffix	The repeating production sequence (alpha).

Definition at line 121 of file rule_macros.h.

TK

#define TK

(

tk

)

{ .ty = RDESC_TOKEN, .id = PREFIX_TK(tk) }

Macro to create a terminal (token) production symbol.

Definition at line 56 of file rule_macros.h.