list.c File Reference

S-expression analyser, reader, writer, and display for list literals. More...

#include "x-type/list.h"
#include "x-type/buffer.h"
#include "x-type/symbol.h"
#include "x-eval.h"
#include "x-heap.h"
#include "x-token.h"
#include "x-token/sexp/list.h"
#include "x-token/sexp/whitespace.h"

Functions
x_obj_t *	x_sexp_list_analyse (x_obj_t *p_base, x_obj_t *p_args)
x_obj_t *	x_sexp_list_delimit (x_obj_t *p_base, x_obj_t *p_args)
static x_obj_t *	x_sexp_list_read_next (x_obj_t *p_base, x_obj_t *p_args)
x_obj_t *	x_sexp_list_read (x_obj_t *p_base, x_obj_t *p_args)

Variables
x_satom_t	x_sexp_list_analyse_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_analyse })
x_satom_t	x_sexp_list_delimit_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_delimit })
x_satom_t	x_sexp_list_read_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_read })

Detailed Description

S-expression analyser, reader, writer, and display for list literals.

Author

Jon Ruttan (jonru.nosp@m.ttan.nosp@m.@gmai.nosp@m.l.co.nosp@m.m)

Copyright

2023 Jon Ruttan @license MIT No Attribution (MIT-0)

Function Documentation

x_sexp_list_analyse()

x_obj_t * x_sexp_list_analyse	(	x_obj_t *	p_base,
		x_obj_t *	p_args
	)

Analyse: score on any list delimiter character.

Matches ( and ) only. Scores the buffer length immediately, which is sound because the brackets really are always single-character tokens.

The dot is NOT matched, and that sentence used to be false of it: a dot scored here on sight, so a token merely BEGINNING with one was taken whole as the pair separator. It is an ordinary character now – the symbol analyser accumulates it, and the list reader recognises the symbol "." when it builds a pair.

Parameters

p_base	Base (execution context).
p_args	Read-args containing the token buffer and score.

Returns

Score on match, or NULL.

x_sexp_list_delimit()

x_obj_t * x_sexp_list_delimit	(	x_obj_t *	p_base,
		x_obj_t *	p_args
	)

Delimiter callback for list characters.

Backs up the read pointer when a list delimiter is encountered so the current token is terminated before the delimiter.

Parameters

p_base	Base (execution context).
p_args	Read-args containing the token buffer.

Returns

The buffer on delimiter match, or NULL.

x_sexp_list_read()

x_obj_t * x_sexp_list_read	(	x_obj_t *	p_base,
		x_obj_t *	p_args
	)

Read a list (or dotted pair) from the token stream.

Two cases, on the bracket character:

• ) – returns the read_prim sentinel (end of list).
• ( – recursively reads elements via x_token_read until the close-paren sentinel, treating the one-character symbol . as the pair separator when it meets one.

The separator has no sentinel of its own. It used to: the dot was a single-character token and this returned delimit_prim for it, which meant every token beginning with a dot became the separator and ... reached the caller as that raw satom, inside a list, as a value.

Parameters

p_base	Base (execution context).
p_args	Read-args containing the token buffer.

Returns

The constructed list, or a sentinel primitive.

x_sexp_list_read_next()

static x_obj_t * x_sexp_list_read_next ( x_obj_t *  p_base, x_obj_t *  p_args  )

static

x_token_read, but end-of-input inside an OPEN list is truncation: raise instead of returning the EOF sentinel. Control never returns, so a partial list can never reach evaluation, and the callers that used to spin appending the ambiguous NULL (#156) terminate loudly. No root-pop before the raise: guard restores the root chain (x-syntax/control.c) and the no-handler path exits – the same protocol as every mid-eval raise.

Parameters

p_base	Base (execution context).
p_args	Read-args containing the token buffer.

Returns

The token object; never the EOF sentinel.

Variable Documentation

x_sexp_list_analyse_prim

x_satom_t x_sexp_list_analyse_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_analyse })

Analyser / delimiter / reader primitive satoms for the list type.

x_sexp_list_delimit_prim

x_satom_t x_sexp_list_delimit_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_delimit })

x_sexp_list_read_prim

x_satom_t x_sexp_list_read_prim = x_obj_set(x_type_atom_obj, X_OBJ_FLAG_NONE, { .fn = x_sexp_list_read })