358 lines
9.8 KiB
C
358 lines
9.8 KiB
C
#include "parse.h"
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#include <stdbool.h>
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#include "map.h"
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#include "runtime.h"
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typedef struct State {
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TokList *toks;
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IRToks *ir;
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} State;
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typedef struct Scope {
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struct Scope *parent;
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size_t mem_addr;
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bool has_idents;
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Map ident_addrs;
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} Scope;
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static void mark_err(const Tok *t);
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static size_t get_ident_addr(const Scope *sc, const char *name, const Tok *errpos);
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static IRParam tok_to_irparam(Scope *sc, Tok *t);
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static Scope make_scope(Scope *parent, size_t mem_addr, bool with_idents);
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static void term_scope(Scope *sc);
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static void expr(State *s, Scope *parent_sc, TokListItem *t, bool toplevel, bool use_storage_addr, size_t storage_addr);
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static void stmt(State *s, Scope *sc, TokListItem *t);
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static void mark_err(const Tok *t) {
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err_ln = t->ln;
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err_col = t->col;
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}
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static size_t get_ident_addr(const Scope *sc, const char *name, const Tok *errpos) {
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size_t addr;
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bool exists = false;
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for (const Scope *i = sc; i != NULL; i = i->parent) {
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if (!i->has_idents)
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continue;
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exists = map_get(&i->ident_addrs, name, &addr);
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if (exists)
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break;
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}
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if (!exists) {
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mark_err(errpos);
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set_err("Identifier '%s' not recognized in this scope", name);
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return 0;
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}
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return addr;
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}
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static IRParam tok_to_irparam(Scope *sc, Tok *t) {
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if (t->kind == TokIdent) {
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size_t addr;
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if (t->Ident.kind == IdentName) {
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TRY_RET(addr = get_ident_addr(sc, t->Ident.Name, t), (IRParam){0});
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} else if (t->Ident.kind == IdentAddr)
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addr = t->Ident.Addr;
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else
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ASSERT_UNREACHED();
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return (IRParam){
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.kind = IRParamAddr,
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.Addr = addr,
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};
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} else if (t->kind == TokVal) {
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return (IRParam){
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.kind = IRParamLiteral,
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.Literal = t->Val,
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};
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} else
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ASSERT_UNREACHED();
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}
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/* term_scope doesn't have to be called if with_idents is set to false. */
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static Scope make_scope(Scope *parent, size_t mem_addr, bool with_idents) {
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Scope s = { .parent = parent, .mem_addr = mem_addr, .has_idents = with_idents };
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if (with_idents)
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map_init(&s.ident_addrs, sizeof(size_t));
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return s;
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}
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static void term_scope(Scope *sc) {
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if (sc->has_idents)
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map_term(&sc->ident_addrs);
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}
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/* If toplevel is set, newlines are seen as delimiters ending the expression.
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* If use_storage_addr is set, the result is guaranteed to be put into storage_addr. */
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static void expr(State *s, Scope *parent_sc, TokListItem *t, bool toplevel, bool use_storage_addr, size_t storage_addr) {
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/* A simplified example of how the operator precedence parsing works:
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* ________________________________
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* Where t points to (between l_op and r_op in each step)
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* |
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* v
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* 5 + 2 * 2 \n
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* ^ ^
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* | |
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* l_op r_op
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* precedence of '+' is higher than that of the front delimiter => move forward
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* ________________________________
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* 5 + 2 * 2 \n
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* ^ ^
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* | |
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* l_op r_op
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* precedence of '*' is higher than that of '+' => move forward
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* ________________________________
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* 5 + 2 * 2 \n
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* ^ ^
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* | |
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* l_op r_op
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* precedence of '\n' (a delimiter) is lower than that of '*' => evaluate and move l_op 2 back
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* ________________________________
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* 5 + 4 \n
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* ^ ^
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* | |
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* l_op r_op
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* precedence of '\n' (a delimiter) is lower than that of '+' => evaluate and move l_op 2 back
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* ________________________________
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* 9 \n
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* ^ ^
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* | |
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* l_op r_op
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* both l_op and r_op are delimiters (their precedence is PREC_DELIM) => done
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*/
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TokListItem *start = t;
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Scope *sc = parent_sc;
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Scope expr_scope_obj;
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if (toplevel) {
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expr_scope_obj = make_scope(parent_sc, parent_sc->mem_addr, false);
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sc = &expr_scope_obj;
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}
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for (;;) {
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/* Prepare to collapse negative factor. */
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bool negate = false;
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if (t->tok.kind == TokOp && t->tok.Op == OpSub) {
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t = t->next;
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negate = true;
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}
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/* Ignore newlines if the expression is not toplevel. */
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if (!toplevel && t->next->tok.kind == TokOp && t->next->tok.Op == OpNewLn)
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toklist_del(s->toks, t->next, t->next);
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/* Collapse negative factor. */
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if (negate) {
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bool is_last_operation = t->prev == start && t->next->tok.kind == TokOp && op_prec[t->next->tok.Op] == PREC_DELIM;
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Tok *v = &t->tok;
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t = t->prev;
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toklist_del(s->toks, t->next, t->next);
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if (v->kind == TokVal) {
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/* immediately negate value */
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t->tok.kind = TokVal;
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t->tok.Val.type.kind = v->Val.type.kind;
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switch (v->Val.type.kind) {
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case TypeInt: t->tok.Val.Int = -v->Val.Int; break;
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case TypeFloat: t->tok.Val.Float = -v->Val.Float; break;
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default: ASSERT_UNREACHED();
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}
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} else {
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/* use the predefined storage address if it was requested and we're on the last operation */
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size_t res_addr;
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if (use_storage_addr && is_last_operation)
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res_addr = storage_addr;
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else
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res_addr = sc->mem_addr++;
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/* add IR instruction to negate the value */
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IRParam v_irparam;
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TRY(v_irparam = tok_to_irparam(sc, v));
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irtoks_app(s->ir, (IRTok){
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.ln = t->tok.ln,
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.col = t->tok.col,
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.instr = IRNeg,
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.Unary = {
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.addr = res_addr,
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.val = v_irparam,
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},
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});
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/* leave new memory address as result */
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t->tok.kind = TokIdent;
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t->tok.Ident = (Identifier){
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.kind = IdentAddr,
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.Addr = res_addr,
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};
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if (use_storage_addr && is_last_operation)
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/* Since the final result was written to the storage address,
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* we're done. */
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return;
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}
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}
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/* Find out operator precedence of l_op and r_op. */
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int8_t l_op_prec;
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Tok *l_op;
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if (t == start) {
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l_op_prec = PREC_DELIM;
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l_op = NULL;
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} else {
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l_op = &t->prev->tok;
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if (l_op->kind != TokOp) {
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mark_err(l_op);
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set_err("Expected operator");
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return;
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}
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l_op_prec = op_prec[l_op->Op];
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}
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int8_t r_op_prec;
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Tok *r_op = &t->next->tok;
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if (r_op->kind != TokOp) {
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mark_err(r_op);
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set_err("Expected operator");
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return;
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}
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r_op_prec = op_prec[r_op->Op];
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/* If l_op and r_op are both delimiters, the expression is fully evaluated.
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* NOTE: Sometimes, we don't reach this point because the function already
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* exits directly after the last operation. */
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if (l_op_prec == PREC_DELIM && r_op_prec == PREC_DELIM) {
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IRParam res;
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TRY(res = tok_to_irparam(sc, &t->tok));
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irtoks_app(s->ir, (IRTok){
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.ln = t->tok.ln,
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.col = t->tok.col,
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.instr = IRSet,
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.Unary = {
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.addr = use_storage_addr ? storage_addr : sc->mem_addr++,
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.val = res,
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},
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});
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toklist_del(s->toks, t, t);
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return;
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}
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bool is_last_operation = t->prev && t->prev->prev == start && r_op_prec == PREC_DELIM;
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/* This is the actual operator precedence parser as described above. */
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if (r_op_prec > l_op_prec)
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t = t->next->next;
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else {
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/* some basic checks */
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Tok *rhs = &t->tok;
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if (rhs->kind != TokVal && rhs->kind != TokIdent) {
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mark_err(rhs);
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set_err("Expected literal or identifier");
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return;
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}
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t = t->prev->prev;
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Tok *lhs = &t->tok;
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if (lhs->kind != TokVal && lhs->kind != TokIdent) {
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mark_err(lhs);
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set_err("Expected literal or identifier");
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return;
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}
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/* delete the tokens that fall away from collapsing the expression
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* (NOTE: only their references are deleted here, that's important
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* because we're still using their values later on) */
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toklist_del(s->toks, t->next, t->next->next);
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IRInstr instr;
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switch (l_op->Op) {
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case OpAdd: instr = IRAdd; break;
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case OpSub: instr = IRSub; break;
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case OpMul: instr = IRMul; break;
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case OpDiv: instr = IRDiv; break;
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default:
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mark_err(l_op);
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set_err("Unknown operation: '%s'", op_str[l_op->Op]);
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return;
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}
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if (lhs->kind == TokVal && rhs->kind == TokVal) {
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/* evaluate the constant expression immediately */
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lhs->kind = TokVal;
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TRY(lhs->Val = eval_arith(instr, &lhs->Val, &rhs->Val));
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} else {
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IRParam lhs_irparam, rhs_irparam;
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TRY(lhs_irparam = tok_to_irparam(sc, lhs));
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TRY(rhs_irparam = tok_to_irparam(sc, rhs));
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/* use the predefined storage address if it was requested and we're on the last operation */
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size_t res_addr;
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if (use_storage_addr && is_last_operation)
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res_addr = storage_addr;
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else
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res_addr = sc->mem_addr++;
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/* emit IR code to evaluate the non-constant expression */
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irtoks_app(s->ir, (IRTok){
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.ln = l_op->ln,
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.col = l_op->col,
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.instr = instr,
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.Arith = {
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.addr = res_addr,
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.lhs = lhs_irparam,
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.rhs = rhs_irparam,
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},
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});
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/* leave new memory address as result */
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lhs->kind = TokIdent;
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lhs->Ident = (Identifier){
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.kind = IdentAddr,
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.Addr = res_addr,
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};
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if (use_storage_addr && is_last_operation)
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/* Since the final result was written to the storage address,
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* we're done. */
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return;
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}
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}
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}
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}
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static void stmt(State *s, Scope *sc, TokListItem *t) {
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TokListItem *start = t;
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if (t->tok.kind == TokIdent && t->tok.Ident.kind == IdentName) {
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char *name = t->tok.Ident.Name;
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t = t->next;
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if (t->tok.kind == TokDeclare) {
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t = t->next;
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size_t addr = sc->mem_addr++;
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bool replaced = map_insert(&sc->ident_addrs, name, &addr);
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if (replaced) {
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mark_err(&start->tok);
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set_err("'%s' already declared in this scope", name);
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return;
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}
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TRY(expr(s, sc, t, true, true, addr));
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} else if (t->tok.kind == TokAssign) {
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t = t->next;
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size_t addr;
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TRY(addr = get_ident_addr(sc, name, &start->tok));
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TRY(expr(s, sc, t, true, true, addr));
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}
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}
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toklist_del(s->toks, start, t);
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}
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IRToks parse(TokList *toks) {
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IRToks ir;
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irtoks_init(&ir);
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State s = { .toks = toks, .ir = &ir };
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Scope global_scope = make_scope(NULL, 0, true);
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for (;;) {
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if (toks->begin->tok.kind == TokOp && toks->begin->tok.Op == OpEOF)
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break;
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TRY_RET(stmt(&s, &global_scope, toks->begin), ir);
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}
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term_scope(&global_scope);
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return ir;
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}
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