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75 lines
2.6 KiB
Text
75 lines
2.6 KiB
Text
// vim: set filetype=none:
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// (Lemon files have .y extensions like Yacc files but are not Yacc.)
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%include {
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#include <stdio.h>
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#include <string.h>
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#include <math.h>
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#include "../lib/mlrutil.h"
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#include "./ex_ast.h"
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#include "../containers/sllv.h"
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#define DO_WRITE_APPEND // transitional pending lemon-memory issue
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// ================================================================
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// AST:
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// * parens, commas, semis, line endings, whitespace are all stripped away
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// * variable names and literal values remain as leaf nodes of the AST
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// * = + - * / ** {function names} remain as non-leaf nodes of the AST
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// CST: See ex0_cst.c
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//
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// Note: This parser accepts many things that are invalid, e.g.
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// * begin{end{}} -- begin/end not at top level
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// * begin{$x=1} -- references to stream records at begin/end
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// * break/continue outside of for/while/do-while
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// * $x=x -- boundvars outside of for-loop variable bindings
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// All of the above are enforced by the CST builder, which takes this parser's output AST as input.
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// This is done (a) to keep this grammar from being overly complex, and (b) so we can get much more
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// informative error messages in C than in Lemon ('syntax error').
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//
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// The parser hooks all build up an abstract syntax tree specifically for the CST builder.
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// For clearer visuals on what the ASTs look like:
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// * See ex0_cst.c
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// * See reg_test/run's filter -v and put -v outputs, e.g. in reg_test/expected/out
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// * Do "mlr -n put -v 'your expression goes here'"
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// ================================================================
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}
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%token_type {ex_ast_node_t*}
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%default_type {ex_ast_node_t*}
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%extra_argument {ex_ast_t* past}
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//void token_destructor(ex_ast_node_t t) {
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// printf("In token_destructor t->text(%s)=t->type(%lf)\n", t->text, t->type);
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//}
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//%token_destructor {token_destructor($$);}
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%parse_accept {
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}
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// The caller is expected to provide more context.
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%syntax_error {
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fprintf(stderr, "mlr DSL: syntax error.\n");
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}
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// ================================================================
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md_body ::= math_expr(B). {
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past->proot = B;
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}
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math_expr(C) ::= MD_TOKEN_NUMBER(A) MD_TOKEN_PLUS(O) MD_TOKEN_NUMBER(B) . {
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C = ex_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_OPERATOR, A, B);
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}
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math_expr(C) ::= MD_TOKEN_NUMBER(A) MD_TOKEN_MINUS(O) MD_TOKEN_NUMBER(B) . {
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C = ex_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_OPERATOR, A, B);
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}
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math_expr(C) ::= MD_TOKEN_NUMBER(A) MD_TOKEN_TIMES(O) MD_TOKEN_NUMBER(B) . {
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C = ex_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_OPERATOR, A, B);
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}
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math_expr(C) ::= MD_TOKEN_NUMBER(A) MD_TOKEN_DIVIDE(O) MD_TOKEN_NUMBER(B) . {
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C = ex_ast_node_alloc_binary(O->text, MD_AST_NODE_TYPE_OPERATOR, A, B);
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}
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