first draft of new parser
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fumfar hiwi
+177
@@ -0,0 +1,177 @@
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namespace Parser {
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proc eat_comment_line(char* text, int* index_in_text) -> void {
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// safety check if we are actually starting a comment here
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if (text[*index_in_text] != ';')
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return;
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// eat the comment line
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do {
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++(*index_in_text);
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++parser_col;
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} while (text[(*index_in_text)] != '\n' &&
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text[(*index_in_text)] != '\r' &&
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text[(*index_in_text)] != '\0');
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}
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proc eat_whitespace(char* text, int* index_in_text) -> void {
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// skip whitespaces
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while (text[(*index_in_text)] == ' ' ||
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text[(*index_in_text)] == '\t' ||
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text[(*index_in_text)] == '\n' ||
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text[(*index_in_text)] == '\r')
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{
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if (text[(*index_in_text)] == '\n') {
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++parser_line;
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parser_col = 0;
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}
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++parser_col;
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++(*index_in_text);
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}
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}
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proc eat_until_code(char* text, int* index_in_text) -> void {
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int position_before;
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do {
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position_before = *index_in_text;
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eat_comment_line(text, index_in_text);
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eat_whitespace(text, index_in_text);
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} while (position_before != *index_in_text);
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}
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proc step_char(int* index_in_text) {
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++(*index_in_text);
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++parser_col;
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}
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proc step_char_and_eat_until_code(char* text, int* index_in_text) {
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step_char(index_in_text);
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eat_until_code(text, index_in_text);
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}
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proc parse_fancy_delimiter(char* text, int* index_in_text, char l_delimiter, char r_delimiter, Lisp_Object* first_elem) -> Lisp_Object* {
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if (text[*index_in_text] != l_delimiter) {
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create_parsing_error("a fancy cannot be parsed here");
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return nullptr;
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}
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Lisp_Objcet* ret;
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Lisp_Objcet* head;
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try ret = Memory::create_lisp_object_pair(first_elem, Memory::nil);
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head = ret;
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step_char(index_in_text);
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while (text[*index_in_text] != r_delimiter) {
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eat_until_code(text, index_in_text);
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Lisp_Object* element;
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try element = parse_expression(text, index_in_text);
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try head.value.pair.rest = Memory::create_lisp_object_pair(element, Memory::nil);
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head = head.value.pair.rest;
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}
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++*index_in_text;
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return ret;
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}
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proc parse_list(char* text, int* index_in_text) -> Lisp_Object* {
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if (text[*index_in_text] != '(') {
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create_parsing_error("a list cannot be parsed here");
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return nullptr;
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}
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step_char_and_eat_until_code();
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if (text[*index_in_text] == ')') {
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return meory::nil;
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}
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Lisp_Object* first_elem;
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Lisp_Objcet* ret;
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Lisp_Objcet* head;
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try first_elem = parse_epression(text, index_in_text);
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try ret = Memory::create_lisp_object_pair(first_elem, Memory::nil);
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head = ret;
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while (text[*index_in_text] != r_delimiter) {
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eat_until_code(text, index_in_text);
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Lisp_Object* element;
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try element = parse_expression(text, index_in_text);
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try head.value.pair.rest = Memory::create_lisp_object_pair(element, Memory::nil);
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head = head.value.pair.rest;
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}
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}
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proc maybe_expand_short_form(char* text, int* index_in_text) -> Lisp_Object* {
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Lisp_Object* vector_sym = Memory::get_or_create_lisp_object_symbol("vector");
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Lisp_Object* hash_map_sym = Memory::get_or_create_lisp_object_symbol("hash-map");
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Lisp_Object* quote_sym = Memory::get_or_create_lisp_object_symbol("quote");
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Lisp_Object* quasiquote_sym = Memory::get_or_create_lisp_object_symbol("quasiquote");
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Lisp_Object* unquote_sym = Memory::get_or_create_lisp_object_symbol("unquote");
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Lisp_Object* unquote_splicing_sym = Memory::get_or_create_lisp_object_symbol("unquote-splicing");
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Lisp_Object* ret;
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Lisp_Object* expr;
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switch (text[*index_in_text]) {
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case '\'': {
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// quote
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step_char_and_eat_until_code(text, index_in_text);
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expr = parse_expresion(text, index_in_text);
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try ret = Memory::create_lisp_object_pair(quote_sym, expr);
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} break;
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case '`': {
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// quasiquote
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step_char_and_eat_until_code(text, index_in_text);
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expr = parse_expresion(text, index_in_text);
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try ret = Memory::create_lisp_object_pair(quasiquote_sym, expr);
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} break;
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case ',': {
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if (text[*index_in_text+1] == '@') {
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// unquote-splicing
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step_char(text, index_in_text);
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step_char_and_eat_until_code(itext, index_in_text);
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expr = parse_expresion(text, index_in_text);
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try ret = Memory::create_lisp_object_pair(unquote_splicing_sym, expr);
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} else {
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// unquote
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expr = parse_expresion(text, index_in_text);
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try ret = Memory::create_lisp_object_pair(unquote_sym, expr);
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step_char_and_eat_until_code(text, index_in_text);
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}
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} break;
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case '[': {
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// vector
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try ret = parse_fancy_delimiter(text, index_in_text, '[', ']', vector_sym);
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} break;
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case '{': {
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// hashmap
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try ret = parse_fancy_delimiter(text, index_in_text, '{', '}', hash_map_sym);
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try parse_hash_map(text, index_in_text);
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} break;
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default: break;
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}
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return ret;
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}
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proc parse_expression(char* text, int* index_in_text) -> Lisp_Object* {
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Lisp_Object* ret;
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try ret = maybe_expand_short_form(text, index_in_text);
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if (ret)
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return ret;
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if (text[*index_in_text] == '(') {
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try ret = parse_list(text, index_in_text);
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}
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}
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}
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