parsing and environment infrastructure
. add env struct and parameter, . add lookup() and append() functions . add `q` and `add` in eval,
This commit is contained in:
Christian Barthel
parent
3ba49003f3
commit
ca33a1096c
243
tokenize.l
243
tokenize.l
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@ -1,6 +1,7 @@
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/*
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* flex tokenize.l
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* cc lex.yy.c -lfl
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/* llm - litle lisp machine:
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* Author: Christian Barthel <bch@online.de>
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* Compile: flex tokenize.l
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* cc lex.yy.c -lfl
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*/
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%{
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#include <assert.h>
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@ -11,26 +12,34 @@ struct token;
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struct token {
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int type;
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union {
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char *str;
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int num;
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char *str;
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int num;
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} v;
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struct token *next;
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};
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struct ast;
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struct ast {
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int type;
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int type;
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union {
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struct token *token;
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struct ast *list;
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struct ast *list;
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} v;
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struct ast *next;
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struct ast *next;
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};
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struct env;
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struct env {
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char *name;
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struct ast *a;
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struct env *parent;
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struct env *next;
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};
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enum asttype {
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AST_TOK = 400,
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AST_LIST = 401
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AST_LIST = 401,
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AST_QUOTE = 402
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};
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enum yytokentype {
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NUM = 258,
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@ -38,7 +47,8 @@ enum yytokentype {
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RPAR = 260,
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SYM = 261,
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STR = 262,
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EOL = 263
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EOL = 263,
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QUOTE = 264
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};
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struct token *make_token(enum yytokentype, int, char*);
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@ -47,32 +57,62 @@ char *yystr;
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%}
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%%
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"(" { return LPAR; }
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")" { return RPAR; }
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[0-9]+ { yylval = atoi(yytext); return NUM; }
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\n { return EOL; }
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[ \t\n] { /* ignore white space */ }
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\".*\" { return STR; }
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[a-zA-Z][a-zA-Z0-9]* { return SYM; }
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. { err(1, "invalid symbol: %s\n", yytext); }
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"(" { return LPAR; }
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")" { return RPAR; }
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[0-9]+ { yylval = atoi(yytext); return NUM; }
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\n { return EOL; }
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[ \t\n] { /* ignore white space */ }
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\".*\" { return STR; }
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[a-zA-Z][a-zA-Z0-9]* { return SYM; }
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. { err(1, "invalid symbol: %s\n", yytext); }
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%%
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/*
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* Goal: write LISP read-eval-print Loop and support
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* @ Function
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* 0,1 boolean (nand 0 1) -> boolean
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* (eq 0 0) -> boolean
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* "str" Strings (streq str1 str2) -> boolean
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* abc Symboles (symeq s1 s2) -> boolean
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* 1234 Number/Integer [add,sub,div,mul,mod] -> number
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* [lt, numeq] -> boolean
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* [num2bool] -> boolean
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* @ Function
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* 0,1 boolean (nand 0 1) -> boolean
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* (eq 0 0) -> boolean
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* "str" Strings (streq str1 str2) -> boolean
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* abc Symboles (symeq s1 s2) -> boolean
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* 1234 Number/Integer [add,sub,div,mul,mod] -> num
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* [lt, numeq] -> boolean
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* [num2bool] -> boolean
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*
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* (def <var> <symbol,number,#function)
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* (lambda (<symbol> ..) (<sym..> ))
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* (if <bool> <body> <else>)
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* (quote a) -> a
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*/
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void
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debug_token(struct token *x, int indent) {
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for (int i = 0; i < indent; i++) putc(' ', stderr);
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fprintf(stderr, "%d: (%p)", x->type, x);
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if (x->type == NUM) fprintf(stderr, "%d @ %p", x->v.num, x);
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if (x->type == STR || x->type == SYM)
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fprintf(stderr, "%s", x->v.str);
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putc('\n', stderr);
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}
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void
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debug_ast(struct ast *a, int indent) {
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while (a) {
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for (int i = 0; i < indent; i++) putc(' ', stderr);
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fprintf(stderr, "AST: %s,a=%p,list=%p,token=%p,next=%p", (a->type == AST_TOK) ? "AST_TOK" :
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"AST_LIST", a, a->v.list, a->v.token, a->next);
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putc('\n', stderr);
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if (a->type == AST_LIST) {
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fprintf(stderr, "enter %p\n", a->v.list);
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fprintf(stderr, "==\n");
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debug_ast(a->v.list, indent+4);
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fprintf(stderr, "==\n");
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}
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else if(a->type == AST_TOK)
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debug_token(a->v.token, indent);
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a = a->next;
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}
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}
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struct token*
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make_token(enum yytokentype type, int num, char* str)
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{
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@ -91,7 +131,8 @@ make_token(enum yytokentype type, int num, char* str)
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struct ast*
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make_ast(enum asttype type, struct token *t)
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{
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struct ast *a = (struct ast*) calloc(1, sizeof(struct ast));
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struct ast *a =
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(struct ast*) calloc(1, sizeof(struct ast));
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if (a == NULL)
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err(1, "malloc failed");
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a->type = type;
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@ -102,6 +143,25 @@ make_ast(enum asttype type, struct token *t)
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return a;
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}
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struct env*
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make_env(char *name, struct ast *a)
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{
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struct env *e =
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(struct env*) calloc(1, sizeof(struct env));
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if (e == NULL)
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err(1, "malloc failed");
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e->name = name;
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e->a = a;
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return e;
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}
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/* upon parsing a list of tokens like:
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* "(" -> "def" -> "(" -> "b" -> ")" -> "c" -> ")"
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* care must be taken when entering a new sub-list (b),
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* because the processing in the upper level must continue
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* where the sub-list ended, i.e. "c" must be the next
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* token on this level.
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*/
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struct token *next;
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struct ast*
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parse(struct token *t)
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@ -118,85 +178,113 @@ parse(struct token *t)
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a = parse(t);
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if (a == NULL)
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err(1, "syntax error");
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if (head->v.list == NULL) {
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if (head->v.list == NULL)
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p = head->v.list = a;
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} else {
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else
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p->next = a;
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}
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p = a;
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t = next; /* skip all tokens that are processed */
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t = next; /* skip all tokens that are processed */
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assert(t != NULL);
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}
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fprintf(stderr, "a=%p, t=%p\n", a, t);
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assert(t->type == RPAR);
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t = t->next;
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next = t;
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return head;
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} else if (t->type == NUM) {
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printf("is a number %d\n", t->v.num);
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next = t->next;
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return make_ast(AST_TOK, t);
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} else if (t->type == SYM) {
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printf("is a sym: %s (%p)\n", t->v.str, t);
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next = t->next;
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return make_ast(AST_TOK, t);
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} else if (t->type == STR) {
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next = t->next;
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printf("is a str: %s\n", t->v.str);
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return make_ast(AST_TOK, t);
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}
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return NULL;
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}
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void
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debug_token(struct token *x, indent) {
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for (int i = 0; i < indent; i++) putc(' ', stderr);
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fprintf(stderr, "%d: (%p)", x->type, x);
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if (x->type == NUM) fprintf(stderr, "%d @ %p", x->v.num, x);
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if (x->type == STR || x->type == SYM)
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fprintf(stderr, "%s", x->v.str);
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putc('\n', stderr);
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}
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void
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debug_ast(struct ast *a, indent) {
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while (a) {
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for (int i = 0; i < indent; i++) putc(' ', stderr);
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fprintf(stderr, "AST: %s,a=%p,list=%p,token=%p,next=%p", (a->type == AST_TOK) ? "AST_TOK" :
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"AST_LIST", a, a->v.list, a->v.token, a->next);
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putc('\n', stderr);
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if (a->type == AST_LIST) {
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fprintf(stderr, "enter %p\n", a->v.list);
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fprintf(stderr, "==\n");
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debug_ast(a->v.list, indent+4);
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fprintf(stderr, "==\n");
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}
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else if(a->type == AST_TOK)
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debug_token(a->v.token, indent);
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a = a->next;
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}
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append(struct env *e, struct env *a)
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{
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if (e->next == NULL) {
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e->next = a;
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return;
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} else
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append(e->next, a);
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}
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struct ast *
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eval(struct ast *a)
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lookup(struct env *e, char *name)
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{
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if (e == NULL)
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return NULL;
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for (struct env *t = e; t != NULL; t = t->next)
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if (strcmp(t->name, name) == 0)
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return t->a;
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return lookup(e->parent, name);
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}
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struct ast *
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eval(struct ast *a, struct env *e)
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{
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if (a == NULL) return NULL;
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if (a->type == AST_TOK) {
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if (a->v.token->type == NUM) {
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return make_ast(AST_TOK, a->v.token);
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}
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else if (a->v.token->type == SYM) {
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fprintf(stderr, "process: %s\n", a->v.token->v.str);
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if (strcmp(a->v.token->v.str, "def") == 0) {
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printf("define: %s\n", a->next->v.token->v.str);
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/* x = eval a->next->next */
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/* install: var:=x */
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a = a->next;
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assert((a->next->type == AST_TOK &&
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a->next->v.token->type== STR) ||
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(a->next->type == AST_TOK &&
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a->next->v.token->type == NUM) ||
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(a->next->type == AST_LIST) ||
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(a->next->type == AST_TOK &&
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a->next->v.token->type== SYM));
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append(e, make_env(a->v.token->v.str, eval(a->next, e)));
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return NULL;
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} else if (strcmp(a->v.token->v.str, "lm") == 0) {
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} else if (strcmp(a->v.token->v.str, "if") == 0) {
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} else if (strcmp(a->v.token->v.str, "add") == 0) {
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assert (a != NULL &&
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a->next != NULL &&
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a->next->next != NULL &&
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a->next->next->next == NULL);
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struct ast *op1 = eval(a->next, e);
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struct ast *op2 = eval(a->next->next, e);
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assert (op1 != NULL &&
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op1->type == AST_TOK &&
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op1->v.token->type == NUM &&
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op2 != NULL &&
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op2->type == AST_TOK &&
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op2->v.token->type == NUM);
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return make_ast(AST_TOK,
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make_token(NUM,
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op1->v.token->v.num +
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op2->v.token->v.num,
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NULL));
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} else if (strcmp(a->v.token->v.str, "q") == 0) {
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//return make_ast(AST_QUOTE, a->next);
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return a->next;
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} else {
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// fprintf(stderr, "Lookup: %s\n", a->v.token->v.str);
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struct ast *var = lookup(e, a->v.token->v.str);
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assert(var != NULL); /* variable found? */
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return var;
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}
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/* XXX: nand, eq, streq, symeq, add, sub, div, mul,
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* mod, lt, numeq, num2bool
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*/
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} else if (a->v.token->type == STR)
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fprintf(stderr, "str\n");
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return make_ast(AST_TOK, a->v.token);
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} else if (a->type == AST_LIST) {
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eval(a->v.list);
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return eval(a->v.list, e);
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} else {
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fprintf(stderr, "%d\n", a->type);
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assert(0);
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@ -207,10 +295,18 @@ eval(struct ast *a)
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void
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pr(struct ast *a)
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{
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if (a == NULL) {
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fprintf(stderr, "null %p\n", a);
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return;
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}
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switch (a->type) {
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case AST_TOK:
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if (a->v.token->type == NUM)
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printf("%d\n", a->v.token->v.num);
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else if (a->v.token->type == STR)
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printf("%s\n", a->v.token->v.str);
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else if (a->v.token->type == SYM)
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printf("%s\n", a->v.token->v.str);
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}
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}
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@ -218,8 +314,11 @@ int main(void)
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{
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int tok;
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struct token *t, *u = NULL, *start = NULL;
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struct env default_env = { 0 }, *env;
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env = &default_env;
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env->name = "";
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while(tok = yylex()) {
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while((tok = yylex())) {
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/* read token and create list */
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t = make_token(tok, yylval, yytext);
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if (start == NULL) start = t;
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@ -234,7 +333,7 @@ int main(void)
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/* struct ast *tl = parse(start); */
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/* eval(tl); */
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eval(parse(start));
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pr(eval(parse(start), env));
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//debug_ast(tl, 1);
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/* start anew: */
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