path: root/parse.c

#include "parse.h"

#include <errno.h>
#include <string.h>
#include <assert.h>

#include "macro.h"
#include "vcal.h"

#include "err.h"

#define TYPE vcomponent
#include "linked_list.inc.h"
#undef TYPE

#define T strbuf
#define V strbuf
#include "pair.h"
#include "pair.inc.h"
#undef T
#undef V

/*
 * Input
 *   f: file to get characters from
 *   ctx: current parse context
 *   c: last read character
 * output:
 *   0: line folded
 *   1: line ended
 *
 * A carrige return means that the current line is at an
 * end. The following character should always be \n.
 * However, if the first character on the next line is a
 * whitespace then the two lines should be concatenated.
 *
 * NOTE
 * The above is true according to the standard. But I have
 * found files with only NL. The code below ends line on the
 * first of NL or CR, and then ensures that the program thinks
 * it got the expected CRNL.
 */
int fold(FILE* f, parse_ctx* ctx, char c) {
	int retval;

	char buf[2] = {
		(c == '\n' ? '\n' : fgetc(f)),
		fgetc(f)
	};

	ctx->pcolumn = 1;

	if (buf[0] != '\n') {
		ERR_P(ctx, "expected newline after CR");
		retval = -1;

	} else if (buf[1] == ' ' || buf[1] == '\t') {
		retval = 0;
		ctx->pcolumn++;

	} else if (ungetc(buf[1], f) != buf[1]) {
		ERR_P(ctx, "Failed to put character back on FILE");
		retval = -2;

	} else {
		retval = 1;
		++ctx->line;
		ctx->column = 0;
	}

	++ctx->pline;

	return retval;
}

/*
 * name *(";" param) ":" value CRLF
 */
int parse_file(char* filename, FILE* f, vcomponent* root) {
	part_context p_ctx = p_key;

	SNEW(parse_ctx, ctx, filename);
	PUSH(LLIST(vcomponent))(&ctx.comp_stack, root);

	SNEW(content_line, cline);

	char c;
	while ( (c = fgetc(f)) != EOF) {

		/* We have a linebreak */
		if (c == '\r' || c == '\n') {

			if (fold(f, &ctx, c) > 0) {
				/* Actuall end of line, handle value */

				strbuf* target = CLINE_CUR_VAL(&cline);

				DEEP_COPY(strbuf)(target, &ctx.str);
				strbuf_cap(target);
				strbuf_soft_reset(&ctx.str);

				handle_kv(&cline, &ctx);

				p_ctx = p_key;
			} /* Else continue on current line */

		/* We have an escaped character */
		} else if (c == '\\') {
			char esc = fgetc(f);
			char target;

			/*
			 * An actuall linebreak after the backslash. Unfold the
			 * line and find the next "real" character, and escape
			 * that.
			 */
			if (esc == '\r' || esc == '\n') {
				int ret;
				if ( (ret = fold(f, &ctx, esc)) != 0) {
					if (ret == 1) ERR_P(&ctx, "ESC before not folded line");
					else          ERR_P(&ctx, "other error: val = %i", ret);
					exit (2);
				} else {
					esc = fgetc(f);
				}
			}

			/* Escaped newline */
			if (esc == 'n' || esc == 'N') {
				target = '\n';

			/* "Standard" escaped character */
			} else if (esc == ';' || esc == ',' || esc == '\\') {
				target = esc;

			/* Invalid escaped character */
			} else {
				ERR_P(&ctx, "Non escapable character '%c' (%i)", esc, esc);
			}

			/* save escapade character as a normal character */
			strbuf_append(&ctx.str, target);

			++ctx.column;
			++ctx.pcolumn;


		/* Border between param {key, value} */
		} else if (p_ctx == p_param_name && c == '=') {
			LLIST(param_set)* params = CLINE_CUR_PARAMS(&cline);

			NEW(param_set, ps);
			DEEP_COPY(strbuf)(&ps->key, &ctx.str);
			strbuf_cap(&ps->key);
			strbuf_soft_reset(&ctx.str);
			PUSH(LLIST(param_set))(params, ps);

			p_ctx = p_param_value;

		/*
		 * One of four cases:
		 * 1) end of key  , start of value
		 * 2)   ,,   key  ,    ,,    param
		 * 3)   ,,   param,    ,,    param
		 * 4)   ,,   param,    ,,    value
		 */
		} else if ((p_ctx == p_key || p_ctx == p_param_value) && (c == ':' || c == ';')) {

			if (p_ctx == p_param_value) {
				/* push kv pair */

				NEW(strbuf, s);

				DEEP_COPY(strbuf)(s, &ctx.str);
				strbuf_cap(s);
				strbuf_soft_reset(&ctx.str);

				LLIST(strbuf)* ls = & CLINE_CUR_PARAMS(&cline)->cur->value->val;
				PUSH(LLIST(strbuf))(ls, s);

			}

			if (p_ctx == p_key) {
				DEEP_COPY(strbuf)(&cline.key, &ctx.str);
				strbuf_cap(&cline.key);
				strbuf_soft_reset(&ctx.str);

				NEW(content_set, p);
				PUSH(LLIST(content_set))(&cline.val, p);
			}

			if      (c == ':') p_ctx = p_value;
			else if (c == ';') p_ctx = p_param_name;

		} else {
			strbuf_append(&ctx.str, c);

			++ctx.column;
			++ctx.pcolumn;
		}
	}

	if (! feof(f)) {
		ERR("Error parsing");
	}
	/* Check to see if empty line */
	else if (ctx.str.ptr != 0) {
		/*
		 * The standard (3.4, l. 2675) says that each icalobject must
		 * end with CRLF. My files however does not, so we also parse
		 * the end here.
		 */

		strbuf* target = CLINE_CUR_VAL(&cline);
		DEEP_COPY(strbuf)(target, &ctx.str);
		strbuf_cap(target);
		strbuf_soft_reset(&ctx.str);

		++ctx.line;
		ctx.column = 0;

		handle_kv(&cline, &ctx);

	}

	FREE(content_line)(&cline);

	assert(POP(LLIST(vcomponent))(&ctx.comp_stack) == root);
	assert(EMPTY(LLIST(strbuf))(&ctx.key_stack));
	assert(EMPTY(LLIST(vcomponent))(&ctx.comp_stack));

	FREE(parse_ctx)(&ctx);

	return 0;
}

int handle_kv (
	content_line* cline,
	parse_ctx* ctx
	) {

	if (strbuf_c(&cline->key, "BEGIN")) {
		/* should be one of:
		 * VCALENDAR, VEVENT, VALARM, VTODO, VTIMEZONE,
		 * and possibly some others I forget.
		 */

		NEW(strbuf, s);
		strbuf* type = CLINE_CUR_VAL(cline);
		DEEP_COPY(strbuf)(s, type);
		PUSH(LLIST(strbuf))(&ctx->key_stack, s);

		RESET(LLIST(content_set))(&cline->val);

		NEW(vcomponent, e,
				s->mem,
				ctx->filename);
		e->parent = PEEK(LLIST(vcomponent))(&ctx->comp_stack);
		PUSH(LLIST(vcomponent))(&ctx->comp_stack, e);

	} else if (strbuf_c(&cline->key, "END")) {
		strbuf* s = POP(LLIST(strbuf))(&ctx->key_stack);
		if (strbuf_cmp(s, CLINE_CUR_VAL(cline)) != 0) {
			ERR_P(ctx, "Expected END:%s, got END:%s.\n%s line",
					s->mem,
					CLINE_CUR_VAL(cline)->mem,
					PEEK(LLIST(vcomponent))(&ctx->comp_stack)->filename);
			PUSH(LLIST(strbuf))(&ctx->key_stack, s);
			return -1;

		} else {
			FFREE(strbuf, s);
			/* Received propper end, push cur into parent */
			vcomponent* cur = POP(LLIST(vcomponent))(&ctx->comp_stack);

			// TODO should this instead be done at creation time?
			PUSH(vcomponent)(PEEK(LLIST(vcomponent))(&ctx->comp_stack), cur);
		}
	} else {
		NEW(content_line, c);
		DEEP_COPY(content_line)(c, cline);

		PUSH(TRIE(content_line))(
				&PEEK(LLIST(vcomponent))(&ctx->comp_stack)->clines,
				c->key.mem, c);

		RESET(LLIST(content_set))(&cline->val);
	}

	return 0;
}

INIT_F(parse_ctx, char* filename) {
	INIT(LLIST(strbuf), &this->key_stack);
	INIT(LLIST(vcomponent), &this->comp_stack);
	this->filename = calloc(sizeof(*filename), strlen(filename) + 1);
	strcpy(this->filename, filename);

	this->line    = 0;
	this->column  = 0;

	this->pline   = 1;
	this->pcolumn = 1;

	INIT(strbuf, &this->str);

	return 0;
}

FREE_F(parse_ctx) {

	FREE(LLIST(strbuf))(&this->key_stack);
	FREE(LLIST(vcomponent))(&this->comp_stack);
	free(this->filename);

	this->line = 0;
	this->column = 0;
	FREE(strbuf)(&this->str);

	return 0;
}