ref: a062a0574fa9bbff7f3cb62251b41d42a441440f
dir: /parse.c/
#include <u.h>
#include <libc.h>
#include <thread.h>
#include "dat.h"
#include "fns.h"
static int peek(TokenList *);
static int peekclass(TokenList *);
static void match(TokenList *, int);
static void addchild(Ast *, Ast *);
static int issep(TokenList *t);
static int isexprsep(TokenList *t);
static int nameclass(char *, Symtab *, Ast *);
static void parsesep(TokenList *);
static void parseseps(TokenList *, int);
static Ast *parseprog(TokenList *);
static Ast *parsefuncdef(TokenList *);
static Ast *parsefuncheader(TokenList *);
static Ast *parselocals(TokenList *);
static Ast *parseexpr(TokenList *, Symtab *, Ast *);
static Ast *parseexprsub(TokenList *);
static Ast *parseline(TokenList *);
static Ast *parsename(TokenList *);
static Ast *parsefunc(TokenList *);
static Ast *parseconst(TokenList *);
Ast *
parse(TokenList *tokens, Symtab *symtab)
{
Ast *ast;
tokens->offset = 0;
if(symtab)
ast = parseexpr(tokens, symtab, nil);
else
ast = parseprog(tokens);
match(tokens, TokEnd);
return ast;
}
static int
peek(TokenList *tokens)
{
if(tokens->offset >= tokens->count)
error(ESyntax, "unexpected end of token stream");
return tokens->tokens[tokens->offset].tag;
}
static int
peekclass(TokenList *tokens)
{
peek(tokens); /* triggers an error if we are at the end */
return tokens->tokens[tokens->offset].nameclass;
}
static void
match(TokenList *tokens, int tag)
{
if(peek(tokens) != tag)
error(ESyntax, "Unexpected token: %s", printtok(tokens->tokens[tokens->offset]));
tokens->offset++;
}
static void
addchild(Ast *ast, Ast *child)
{
ast->childcount++;
ast->children = allocextra(ast, sizeof(Ast *) * ast->childcount);
ast->children[ast->childcount-1] = child;
}
static int
issep(TokenList *t)
{
switch(peek(t)){
case TokNewline:
case TokDiamond:
return 1;
default:
return 0;
}
}
static int
isexprsep(TokenList *t)
{
switch(peek(t)){
case TokNewline:
case TokDiamond:
case TokDel:
case TokEnd:
return 1;
default:
return 0;
}
}
static int
nameclass(char *name, Symtab *s, Ast *func)
{
int class = NameclassUndef;
if(func == nil)
class = NameclassUndef;
else if(strcmp(name, func->funcname->name) == 0)
class = NameclassFunc;
else if(func->funcresult && strcmp(name, func->funcresult->name) == 0)
class = NameclassLocal;
else if(func->funcleftarg && strcmp(name, func->funcleftarg->name) == 0)
class = NameclassLocal;
else if(func->funcrightarg && strcmp(name, func->funcrightarg->name) == 0)
class = NameclassLocal;
if(s && class == NameclassUndef){
uvlong symid = sym(s, name);
void *val = symval(s, symid);
if(val) switch(getalloctag(val)){
case DataArray:
class = NameclassArray;
break;
case DataFunction:
class = NameclassFunc;
break;
/* more cases here in the future */
}
}
/* TODO: Check if the name exist in the locallist */
return class;
}
static void
parsesep(TokenList *t)
{
if(issep(t))
match(t, peek(t));
}
static void
parseseps(TokenList *t, int required)
{
while(issep(t)){
match(t, peek(t));
required = 0;
}
if(required)
match(t, TokNewline);
}
static Ast *
parseprog(TokenList *t)
{
Ast *prog = alloc(DataAst);
prog->tag = AstProg;
while(peek(t) != TokEnd){
Ast *child;
if(peek(t) == TokDel)
child = parsefuncdef(t);
else
child = parseexpr(t, nil, nil);
if(peek(t) != TokEnd)
parseseps(t, 1);
addchild(prog, child);
}
return prog;
}
static Ast *
parsefuncdef(TokenList *t)
{
Ast *func = parsefuncheader(t);
while(peek(t) != TokDel){
Ast *expr = parseexpr(t, nil, func);
addchild(func, expr);
if(peek(t) != TokDel)
parseseps(t, 1);
}
match(t, TokDel);
return func;
}
static Ast *
parsefuncheader(TokenList *t)
{
Ast *func = alloc(DataAst);
func->tag = AstFunc;
match(t, TokDel);
func->funcname = parsename(t);
if(peek(t) == TokLarrow){
match(t, TokLarrow);
func->funcresult = func->funcname;
func->funcname = parsename(t);
}
if(peek(t) == TokName)
func->funcrightarg = parsename(t);
if(peek(t) == TokName){
func->funcleftarg = func->funcname;
func->funcname = func->funcrightarg;
func->funcrightarg = parsename(t);
}
func->funclocals = parselocals(t);
return func;
}
static Ast *
parselocals(TokenList *t)
{
Ast *locals = alloc(DataAst);
locals->tag = AstLocals;
while(peek(t) == TokSemi){
match(t, TokSemi);
Ast *name = parsename(t);
name->nameclass = NameclassLocal;
addchild(locals, name);
}
parseseps(t, 1);
return locals;
}
static Ast *
parseexpr(TokenList *t, Symtab *symtab, Ast *func)
{
uvlong start, end;
vlong depth;
depth = 0;
start = t->offset;
while(!isexprsep(t) || depth != 0){
switch(peek(t)){
case TokLparen: depth++; break;
case TokRparen: depth--; break;
}
match(t, peek(t));
}
end = t->offset;
t->offset = start;
for(uvlong i = start; i < end; i++){
char *name;
int class;
if(t->tokens[i].tag != TokName)
continue;
if((i+1) < end && t->tokens[i+1].tag == TokLarrow)
continue; /* assignment */
name = t->tokens[i].name;
class = nameclass(name, symtab, func);
t->tokens[i].nameclass = class;
if(class == 0){ /* We don't know how to parse it until runtime */
if(symtab)
error(EValue, "%s is undefined", name);
uvlong count = end-start;
Ast *later = alloc(DataAst);
later->tag = AstLater;
later->tokens = alloc(DataTokenList);
later->tokens->count = count+1;
later->tokens->tokens = allocextra(later->tokens, sizeof(Token) * later->tokens->count);
for(i = 0; i < count; i++){
later->tokens->tokens[i] = t->tokens[start+i];
match(t, peek(t));
}
later->tokens->tokens[count].tag = TokEnd;
return later;
}
}
/* We know the nameclass of each name, and assume that the nameclasses do not change.
* Now create the AST.
*/
return parseexprsub(t);
}
static Ast *
parseexprsub(TokenList *t)
{
Ast *expr, *val, *strand;
strand = nil;
again:
if(peek(t) == TokLparen){
match(t, TokLparen);
val = parseexprsub(t);
match(t, TokRparen);
}else
val = nil;
if(peekclass(t) == NameclassFunc){
func:
expr = alloc(DataAst);
expr->func = parsefunc(t);
if(val == nil && (isexprsep(t) || peek(t) == TokRparen))
expr->tag = AstNiladic;
else{
if(val){
expr->tag = AstDyadic;
expr->left = val;
}else
expr->tag = AstMonadic;
expr->right = parseexprsub(t);
}
val = expr;
goto end;
}
if(peek(t) == TokName){
val = parsename(t);
if(peek(t) == TokLarrow){
match(t, TokLarrow);
expr = alloc(DataAst);
expr->tag = AstAssign;
expr->left = val;
expr->right = parseexprsub(t);
val = expr;
goto end;
}
}
/* We need a value now */
if(val == nil)
val = parseconst(t);
if(peekclass(t) == NameclassFunc)
goto func;
if(!(isexprsep(t) || peek(t) == TokRparen)){ /* Stranding */
if(!strand){
strand = alloc(DataAst);
strand->tag = AstStrand;
}
addchild(strand, val);
goto again;
}
end:
if(strand){
addchild(strand, val);
val = strand;
}
return val;
}
static Ast *
parsename(TokenList *t)
{
Ast *name = alloc(DataAst);
name->tag = AstName;
name->name = t->tokens[t->offset].name;
match(t, TokName);
return name;
}
static Ast *
parsefunc(TokenList *t)
{
Ast *func;
if(peek(t) == TokName && peekclass(t) == NameclassFunc)
func = parsename(t);
else{
func = alloc(DataAst);
func->tag = AstPrim;
func->prim = t->tokens[t->offset].prim;
match(t, TokPrimitive);
}
return func;
}
static Ast *
parseconst(TokenList *t)
{
Ast *val = alloc(DataAst);
val->tag = AstConst;
vlong num = t->tokens[t->offset].num;
match(t, TokNumber);
val->val = allocarray(TypeNumber, 0, 1);
setint(val->val, 0, num);
return val;
}