post-scarcity/src/c/io/print.c

/**
 *  io/print.c
 *
 *  Post Scarcity Software Environment: print.
 *
 *  Print basic Lisp objects..This is :bootstrap layer print; it needs to be
 *  able to print characters, symbols, integers, lists and dotted pairs. I
 *  don't think it needs to be able to print anything else.
 *
 *  (c) 2026 Simon Brooke <simon@journeyman.cc>
 *  Licensed under GPL version 2.0, or, at your option, any later version.
 */

#include <ctype.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
 * wide characters
 */
#include <wchar.h>
#include <wctype.h>
/* libcurl, used for io */
#include <curl/curl.h>

#include "io/fopen.h"
#include "io/io.h"
#include "io/print.h"

#include "memory/node.h"
#include "memory/pointer.h"
#include "memory/pso.h"
#include "memory/pso2.h"
#include "memory/tags.h"

#include "ops/string_ops.h"
#include "payloads/character.h"
#include "payloads/cons.h"
#include "payloads/exception.h"
#include "payloads/integer.h"

#include "ops/truth.h"

struct pso_pointer in_write(struct pso_pointer p, URL_FILE *output,
							bool escape);
							
/**
 * @brief write this character `wc` to this `output` stream, escaping it if
 * 1. `escape` is true; and
 * 2. it is a character which the reader would otherwise not cope with.
 *
 * TODO: this does not yet even nearly cope with all the possible special 
 * cases.
 */							
void write_char( wchar_t wc, URL_FILE * output, bool escape) {
	if (escape && !iswprint(wc)) {
		url_fwprintf(output, L"\\%04x", wc);
		// url_fputwc(L'\\', output);
	} else {
		url_fputwc(wc, output);
	}
}


struct pso_pointer print_string_like_thing(struct pso_pointer p,
										   URL_FILE *output, bool escape) {
	switch (get_tag_value(p)) {
	case KEYTV:
		url_fputwc(L':', output);
		break;
	case STRINGTV:
		if (escape)
			url_fputwc(L'"', output);
		break;
	}

	if (keywordp(p) || stringp(p) || symbolp(p)) {
		for (struct pso_pointer cursor = p; !nilp(cursor);
			 cursor = pointer_to_object(cursor)->payload.string.cdr) {
			wchar_t wc = pointer_to_object(cursor)->payload.string.character;

			write_char( wc, output, escape);
		}
	}

	if (stringp(p)) {
		if (escape)
			url_fputwc(L'"', output);
	}
	
	return p;
}

struct pso_pointer write_list_content(struct pso_pointer p, URL_FILE *output,
									  bool escape) {
	struct pso_pointer result = nil;

	if (consp(p)) {
		for (; consp(p); p = c_cdr(p)) {
			struct pso2 *object = pointer_to_object(p);

			result = in_write(object->payload.cons.car, output, escape);

			if (exceptionp(result))
				break;

			switch (get_tag_value(object->payload.cons.cdr)) {
			case NILTV:
				break;
			case CONSTV:
				url_fputwc(L' ', output);
				break;
			default:
				url_fputws(L" . ", output);
				result = in_write(object->payload.cons.cdr, output, escape);
			}
		}
	} else {
		// TODO: return exception
	}

	return result;
}

/**
 * This is kind of modelled after the implementation of PRIN* variants on page
 * 383 of the aluminium book. It is the inner workings of all PRIN* functions.
 *
 * @param p pointer to the object to print.
 * @param output stream to print to.
 * @param escape if true, print everything so that it can be read by the Lisp
 *		reader; otherwise, print it appropriately for human readers.
 * @return p on success, exception on failure.
 */
struct pso_pointer in_write(struct pso_pointer p, URL_FILE *output,
							bool escape) {
	struct pso2 *object = pointer_to_object(p);
	struct pso_pointer result = nil;

	if (object != NULL) {
		uint32_t v = get_tag_value(p);
		switch (v) {
		case CHARACTERTV:
			write_char(object->payload.character.character, output, escape);
			break;
		case CONSTV:
			url_fputwc(L'(', output);
			result = write_list_content(p, output, escape);
			url_fputwc(L')', output);
			break;
		case INTEGERTV:
			url_fwprintf(output, L"%d",
						 (int64_t)(object->payload.integer.value));
			break;
		case KEYTV:
		case STRINGTV:
		case SYMBOLTV:
			print_string_like_thing(p, output, escape);
			break;
		case NILTV:
			url_fputws(L"nil", output);
			break;
		case READTV:
		case WRITETV:
			url_fwprintf(output, L"<%s stream: ",
						 v == READTV ? "read" : "write");
			in_write(object->payload.stream.meta, output, escape);
			url_fputwc(L'>', output);
			break;
		case TRUETV:
			url_fputwc(L't', output);
			break;
		default:
			// TODO: return exception
		}
	} else {
		// TODO: return exception
	}

	return result;
}

/**
 * This is kind of modelled after the implementation of PRIN* variants on page
 * 383 of the aluminium book. It is the inner workings of all PRIN* functions.
 *
 * @param p pointer to the object to print.
 * @param output stream to print to.
 * @param escape if true, print everything so that it can be read by the Lisp
 *		reader; otherwise, print it appropriately for human readers.
 * @param nl_before if true, print a newline *before* printing `p`.
 * @param nl_after if true, print a newline *after* printing `p`; else a space.
 * @return p on success, exception on failure.
 */
struct pso_pointer write(struct pso_pointer p, struct pso_pointer stream,
						 bool escape, bool nl_before, bool nl_after) {
	struct pso_pointer result = p;
	URL_FILE *output = writep(stream)
						   ? pointer_to_object(stream)->payload.stream.stream
						   : file_to_url_file(stdout);

	if (writep(stream)) {
		inc_ref(stream);

		if (nl_before)
			url_fputwc(L'\n', output);

		result = in_write(p, output, true);

		url_fputwc(nl_after ? L'\n' : L' ', output);

		dec_ref(stream);
	} else {
		result = make_exception(
			c_string_to_lisp_string(L"Bad write stream passed to write."), nil,
			nil, nil);
	}

	return result;
}

/**
 * @brief Simple print for bootstrap layer.
 *
 * @param p pointer to the object to print.
 * @param stream if a pointer to an open write stream, print to there.
 * @return struct pso_pointer `nil`, or an exception if some erroe occurred.
 */
struct pso_pointer c_print(struct pso_pointer p, struct pso_pointer stream) {
	return write(p, stream, true, true, false);
}

/**
 * @brief princ is pretty much like print except things are printed `unescaped`
 */
struct pso_pointer c_princ(struct pso_pointer p, struct pso_pointer stream) {
	return write(p, stream, false, true, false);
}