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author | Nick Coghlan <ncoghlan@gmail.com> | 2007-04-15 12:05:43 (GMT) |
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committer | Nick Coghlan <ncoghlan@gmail.com> | 2007-04-15 12:05:43 (GMT) |
commit | 650f0d06d3574f843f52edd1126ddd9ebd6fac7d (patch) | |
tree | 9116cebfb4031d0ac3b2db7dc0e8c85d82751e59 /Python/symtable.c | |
parent | 6ef6306dd62aa092539298ed69c7c6ffff568e2d (diff) | |
download | cpython-650f0d06d3574f843f52edd1126ddd9ebd6fac7d.zip cpython-650f0d06d3574f843f52edd1126ddd9ebd6fac7d.tar.gz cpython-650f0d06d3574f843f52edd1126ddd9ebd6fac7d.tar.bz2 |
Hide list comp variables and support set comprehensions
Diffstat (limited to 'Python/symtable.c')
-rw-r--r-- | Python/symtable.c | 345 |
1 files changed, 209 insertions, 136 deletions
diff --git a/Python/symtable.c b/Python/symtable.c index e9c9391..68deb0a 100644 --- a/Python/symtable.c +++ b/Python/symtable.c @@ -76,7 +76,7 @@ PySTEntry_New(struct symtable *st, identifier name, _Py_block_ty block, ste->ste_generator = 0; ste->ste_returns_value = 0; - if (PyDict_SetItem(st->st_symbols, ste->ste_id, (PyObject *)ste) < 0) + if (PyDict_SetItem(st->st_blocks, ste->ste_id, (PyObject *)ste) < 0) goto fail; return ste; @@ -172,6 +172,8 @@ static int symtable_exit_block(struct symtable *st, void *ast); static int symtable_visit_stmt(struct symtable *st, stmt_ty s); static int symtable_visit_expr(struct symtable *st, expr_ty s); static int symtable_visit_genexp(struct symtable *st, expr_ty s); +static int symtable_visit_listcomp(struct symtable *st, expr_ty s); +static int symtable_visit_setcomp(struct symtable *st, expr_ty s); static int symtable_visit_arguments(struct symtable *st, arguments_ty); static int symtable_visit_excepthandler(struct symtable *st, excepthandler_ty); static int symtable_visit_alias(struct symtable *st, alias_ty); @@ -186,7 +188,8 @@ static int symtable_implicit_arg(struct symtable *st, int pos); static int symtable_visit_annotations(struct symtable *st, stmt_ty s); -static identifier top = NULL, lambda = NULL, genexpr = NULL; +static identifier top = NULL, lambda = NULL, genexpr = NULL, + listcomp = NULL, setcomp = NULL; #define GET_IDENTIFIER(VAR) \ ((VAR) ? (VAR) : ((VAR) = PyString_InternFromString(# VAR))) @@ -204,14 +207,13 @@ symtable_new(void) return NULL; st->st_filename = NULL; - st->st_symbols = NULL; + st->st_blocks = NULL; if ((st->st_stack = PyList_New(0)) == NULL) goto fail; - if ((st->st_symbols = PyDict_New()) == NULL) + if ((st->st_blocks = PyDict_New()) == NULL) goto fail; st->st_cur = NULL; - st->st_tmpname = 0; st->st_private = NULL; return st; fail: @@ -230,6 +232,7 @@ PySymtable_Build(mod_ty mod, const char *filename, PyFutureFeatures *future) return st; st->st_filename = filename; st->st_future = future; + /* Make the initial symbol information gathering pass */ if (!GET_IDENTIFIER(top) || !symtable_enter_block(st, top, ModuleBlock, (void *)mod, 0)) { PySymtable_Free(st); @@ -238,7 +241,6 @@ PySymtable_Build(mod_ty mod, const char *filename, PyFutureFeatures *future) st->st_top = st->st_cur; st->st_cur->ste_unoptimized = OPT_TOPLEVEL; - /* Any other top-level initialization? */ switch (mod->kind) { case Module_kind: seq = mod->v.Module.body; @@ -267,6 +269,7 @@ PySymtable_Build(mod_ty mod, const char *filename, PyFutureFeatures *future) PySymtable_Free(st); return NULL; } + /* Make the second symbol analysis pass */ if (symtable_analyze(st)) return st; PySymtable_Free(st); @@ -280,7 +283,7 @@ PySymtable_Build(mod_ty mod, const char *filename, PyFutureFeatures *future) void PySymtable_Free(struct symtable *st) { - Py_XDECREF(st->st_symbols); + Py_XDECREF(st->st_blocks); Py_XDECREF(st->st_stack); PyMem_Free((void *)st); } @@ -293,7 +296,7 @@ PySymtable_Lookup(struct symtable *st, void *key) k = PyLong_FromVoidPtr(key); if (k == NULL) return NULL; - v = PyDict_GetItem(st->st_symbols, k); + v = PyDict_GetItem(st->st_blocks, k); if (v) { assert(PySTEntry_Check(v)); Py_INCREF(v); @@ -314,7 +317,7 @@ PyST_GetScope(PySTEntryObject *ste, PyObject *name) if (!v) return 0; assert(PyInt_Check(v)); - return (PyInt_AS_LONG(v) >> SCOPE_OFF) & SCOPE_MASK; + return (PyInt_AS_LONG(v) >> SCOPE_OFFSET) & SCOPE_MASK; } @@ -325,7 +328,7 @@ PyST_GetScope(PySTEntryObject *ste, PyObject *name) it determines which local variables are cell variables; they provide bindings that are used for free variables in enclosed blocks. - There are also two kinds of free variables, implicit and explicit. An + There are also two kinds of global variables, implicit and explicit. An explicit global is declared with the global statement. An implicit global is a free variable for which the compiler has found no binding in an enclosing function scope. The implicit global is either a global @@ -337,24 +340,30 @@ PyST_GetScope(PySTEntryObject *ste, PyObject *name) TODO(jhylton): Discuss nonlocal The symbol table requires two passes to determine the scope of each name. - The first pass collects raw facts from the AST: the name is a parameter - here, the name is used by not defined here, etc. The second pass analyzes - these facts during a pass over the PySTEntryObjects created during pass 1. + The first pass collects raw facts from the AST via the symtable_visit_* + functions: the name is a parameter here, the name is used but not defined + here, etc. The second pass analyzes these facts during a pass over the + PySTEntryObjects created during pass 1. When a function is entered during the second pass, the parent passes the set of all name bindings visible to its children. These bindings - are used to determine if the variable is free or an implicit global. + are used to determine if non-local variables are free or implicit globals. After doing the local analysis, it analyzes each of its child blocks - using an updated set of name bindings. + using an updated set of name bindings. - The children update the free variable set. If a local variable is free - in a child, the variable is marked as a cell. The current function must - provide runtime storage for the variable that may outlive the function's - frame. Cell variables are removed from the free set before the analyze - function returns to its parent. + The children update the free variable set. If a local variable is added to + the free variable set by the child, the variable is marked as a cell. The + function object being defined must provide runtime storage for the variable + that may outlive the function's frame. Cell variables are removed from the + free set before the analyze function returns to its parent. - The sets of bound and free variables are implemented as dictionaries - mapping strings to None. + During analysis, the names are: + symbols: dict mapping from symbol names to flag values (including offset scope values) + scopes: dict mapping from symbol names to scope values (no offset) + local: set of all symbol names local to the current scope + bound: set of all symbol names local to a containing function scope + free: set of all symbol names referenced but not bound in child scopes + global: set of all symbol names explicitly declared as global */ #define SET_SCOPE(DICT, NAME, I) { \ @@ -375,14 +384,14 @@ PyST_GetScope(PySTEntryObject *ste, PyObject *name) */ static int -analyze_name(PySTEntryObject *ste, PyObject *dict, PyObject *name, long flags, +analyze_name(PySTEntryObject *ste, PyObject *scopes, PyObject *name, long flags, PyObject *bound, PyObject *local, PyObject *free, PyObject *global) { if (flags & DEF_GLOBAL) { if (flags & DEF_PARAM) { PyErr_Format(PyExc_SyntaxError, - "name '%s' is local and global", + "name '%s' is parameter and global", PyString_AS_STRING(name)); return 0; } @@ -392,41 +401,37 @@ analyze_name(PySTEntryObject *ste, PyObject *dict, PyObject *name, long flags, PyString_AS_STRING(name)); return 0; } - SET_SCOPE(dict, name, GLOBAL_EXPLICIT); - if (PyDict_SetItem(global, name, Py_None) < 0) + SET_SCOPE(scopes, name, GLOBAL_EXPLICIT); + if (PySet_Add(global, name) < 0) + return 0; + if (bound && (PySet_Discard(bound, name) < 0)) return 0; - if (bound && PyDict_GetItem(bound, name)) { - if (PyDict_DelItem(bound, name) < 0) - return 0; - } return 1; } if (flags & DEF_NONLOCAL) { if (flags & DEF_PARAM) { PyErr_Format(PyExc_SyntaxError, - "name '%s' is local and nonlocal", + "name '%s' is parameter and nonlocal", PyString_AS_STRING(name)); return 0; } - if (!PyDict_GetItem(bound, name)) { + if (!PySet_Contains(bound, name)) { PyErr_Format(PyExc_SyntaxError, "no binding for nonlocal '%s' found", PyString_AS_STRING(name)); return 0; } - SET_SCOPE(dict, name, FREE); + SET_SCOPE(scopes, name, FREE); ste->ste_free = 1; - return PyDict_SetItem(free, name, Py_None) >= 0; + return PySet_Add(free, name) >= 0; } if (flags & DEF_BOUND) { - SET_SCOPE(dict, name, LOCAL); - if (PyDict_SetItem(local, name, Py_None) < 0) + SET_SCOPE(scopes, name, LOCAL); + if (PySet_Add(local, name) < 0) + return 0; + if (PySet_Discard(global, name) < 0) return 0; - if (PyDict_GetItem(global, name)) { - if (PyDict_DelItem(global, name) < 0) - return 0; - } return 1; } /* If an enclosing block has a binding for this name, it @@ -434,21 +439,21 @@ analyze_name(PySTEntryObject *ste, PyObject *dict, PyObject *name, long flags, Note that having a non-NULL bound implies that the block is nested. */ - if (bound && PyDict_GetItem(bound, name)) { - SET_SCOPE(dict, name, FREE); + if (bound && PySet_Contains(bound, name)) { + SET_SCOPE(scopes, name, FREE); ste->ste_free = 1; - return PyDict_SetItem(free, name, Py_None) >= 0; + return PySet_Add(free, name) >= 0; } /* If a parent has a global statement, then call it global explicit? It could also be global implicit. */ - if (global && PyDict_GetItem(global, name)) { - SET_SCOPE(dict, name, GLOBAL_EXPLICIT); + if (global && PySet_Contains(global, name)) { + SET_SCOPE(scopes, name, GLOBAL_EXPLICIT); return 1; } if (ste->ste_nested) ste->ste_free = 1; - SET_SCOPE(dict, name, GLOBAL_IMPLICIT); + SET_SCOPE(scopes, name, GLOBAL_IMPLICIT); return 1; } @@ -463,35 +468,35 @@ analyze_name(PySTEntryObject *ste, PyObject *dict, PyObject *name, long flags, */ static int -analyze_cells(PyObject *scope, PyObject *free) +analyze_cells(PyObject *scopes, PyObject *free) { - PyObject *name, *v, *w; + PyObject *name, *v, *v_cell; int success = 0; Py_ssize_t pos = 0; - w = PyInt_FromLong(CELL); - if (!w) + v_cell = PyInt_FromLong(CELL); + if (!v_cell) return 0; - while (PyDict_Next(scope, &pos, &name, &v)) { - long flags; + while (PyDict_Next(scopes, &pos, &name, &v)) { + long scope; assert(PyInt_Check(v)); - flags = PyInt_AS_LONG(v); - if (flags != LOCAL) + scope = PyInt_AS_LONG(v); + if (scope != LOCAL) continue; - if (!PyDict_GetItem(free, name)) + if (!PySet_Contains(free, name)) continue; /* Replace LOCAL with CELL for this name, and remove from free. It is safe to replace the value of name in the dict, because it will not cause a resize. */ - if (PyDict_SetItem(scope, name, w) < 0) + if (PyDict_SetItem(scopes, name, v_cell) < 0) goto error; - if (!PyDict_DelItem(free, name) < 0) + if (PySet_Discard(free, name) < 0) goto error; } success = 1; error: - Py_DECREF(w); + Py_DECREF(v_cell); return success; } @@ -526,77 +531,91 @@ check_unoptimized(const PySTEntryObject* ste) { return 0; } -/* Enter the final scope information into the st_symbols dict. +/* Enter the final scope information into the ste_symbols dict. * * All arguments are dicts. Modifies symbols, others are read-only. */ static int -update_symbols(PyObject *symbols, PyObject *scope, +update_symbols(PyObject *symbols, PyObject *scopes, PyObject *bound, PyObject *free, int classflag) { - PyObject *name, *v, *u, *w, *free_value = NULL; + PyObject *name = NULL, *itr = NULL; + PyObject *v = NULL, *v_scope = NULL, *v_new = NULL, *v_free = NULL; Py_ssize_t pos = 0; + /* Update scope information for all symbols in this scope */ while (PyDict_Next(symbols, &pos, &name, &v)) { - long i, flags; + long scope, flags; assert(PyInt_Check(v)); flags = PyInt_AS_LONG(v); - w = PyDict_GetItem(scope, name); - assert(w && PyInt_Check(w)); - i = PyInt_AS_LONG(w); - flags |= (i << SCOPE_OFF); - u = PyInt_FromLong(flags); - if (!u) + v_scope = PyDict_GetItem(scopes, name); + assert(v_scope && PyInt_Check(v_scope)); + scope = PyInt_AS_LONG(v_scope); + flags |= (scope << SCOPE_OFFSET); + v_new = PyInt_FromLong(flags); + if (!v_new) return 0; - if (PyDict_SetItem(symbols, name, u) < 0) { - Py_DECREF(u); + if (PyDict_SetItem(symbols, name, v_new) < 0) { + Py_DECREF(v_new); return 0; } - Py_DECREF(u); + Py_DECREF(v_new); } - free_value = PyInt_FromLong(FREE << SCOPE_OFF); - if (!free_value) + /* Record not yet resolved free variables from children (if any) */ + v_free = PyInt_FromLong(FREE << SCOPE_OFFSET); + if (!v_free) return 0; - /* add a free variable when it's only use is for creating a closure */ - pos = 0; - while (PyDict_Next(free, &pos, &name, &v)) { - PyObject *o = PyDict_GetItem(symbols, name); + itr = PyObject_GetIter(free); + if (!itr) + goto error; + + while ((name = PyIter_Next(itr))) { + v = PyDict_GetItem(symbols, name); - if (o) { - /* It could be a free variable in a method of + /* Handle symbol that already exists in this scope */ + if (v) { + /* Handle a free variable in a method of the class that has the same name as a local or global in the class scope. */ if (classflag && - PyInt_AS_LONG(o) & (DEF_BOUND | DEF_GLOBAL)) { - long i = PyInt_AS_LONG(o) | DEF_FREE_CLASS; - o = PyInt_FromLong(i); - if (!o) { - Py_DECREF(free_value); - return 0; + PyInt_AS_LONG(v) & (DEF_BOUND | DEF_GLOBAL)) { + long flags = PyInt_AS_LONG(v) | DEF_FREE_CLASS; + v_new = PyInt_FromLong(flags); + if (!v_new) { + goto error; } - if (PyDict_SetItem(symbols, name, o) < 0) { - Py_DECREF(o); - Py_DECREF(free_value); - return 0; + if (PyDict_SetItem(symbols, name, v_new) < 0) { + Py_DECREF(v_new); + goto error; } - Py_DECREF(o); + Py_DECREF(v_new); } - /* else it's not free, probably a cell */ + /* It's a cell, or already a free variable in this scope */ + Py_DECREF(name); continue; } - if (!PyDict_GetItem(bound, name)) + /* Handle global symbol */ + if (!PySet_Contains(bound, name)) { + Py_DECREF(name); continue; /* it's a global */ - - if (PyDict_SetItem(symbols, name, free_value) < 0) { - Py_DECREF(free_value); - return 0; } + /* Propagate new free symbol up the lexical stack */ + if (PyDict_SetItem(symbols, name, v_free) < 0) { + goto error; + } + Py_DECREF(name); } - Py_DECREF(free_value); + Py_DECREF(itr); + Py_DECREF(v_free); return 1; +error: + Py_XDECREF(v_free); + Py_XDECREF(itr); + Py_XDECREF(name); + return 0; } /* Make final symbol table decisions for block of ste. @@ -611,59 +630,74 @@ static int analyze_block(PySTEntryObject *ste, PyObject *bound, PyObject *free, PyObject *global) { - PyObject *name, *v, *local = NULL, *scope = NULL, *newbound = NULL; + PyObject *name, *v, *local = NULL, *scopes = NULL, *newbound = NULL; PyObject *newglobal = NULL, *newfree = NULL; int i, success = 0; Py_ssize_t pos = 0; - local = PyDict_New(); - if (!local) + scopes = PyDict_New(); + if (!scopes) goto error; - scope = PyDict_New(); - if (!scope) + local = PySet_New(NULL); + if (!local) goto error; - newglobal = PyDict_New(); + newglobal = PySet_New(NULL); if (!newglobal) goto error; - newfree = PyDict_New(); + newfree = PySet_New(NULL); if (!newfree) goto error; - newbound = PyDict_New(); + newbound = PySet_New(NULL); if (!newbound) goto error; + /* Class namespace has no effect on names visible in + nested functions, so populate the global and bound + sets to be passed to child blocks before analyzing + this one. + */ if (ste->ste_type == ClassBlock) { - /* make a copy of globals before calling analyze_name(), - because global statements in the class have no effect - on nested functions. - */ - if (PyDict_Update(newglobal, global) < 0) - goto error; - if (bound) - if (PyDict_Update(newbound, bound) < 0) + /* Pass down previously bound symbols */ + if (bound) { + if (!PyNumber_InPlaceOr(newbound, bound)) goto error; + Py_DECREF(newbound); + } + /* Pass down known globals */ + if (!PyNumber_InPlaceOr(newglobal, global)) + goto error; + Py_DECREF(newglobal); } + /* Analyze symbols in current scope */ assert(PySTEntry_Check(ste)); assert(PyDict_Check(ste->ste_symbols)); while (PyDict_Next(ste->ste_symbols, &pos, &name, &v)) { long flags = PyInt_AS_LONG(v); - if (!analyze_name(ste, scope, name, flags, bound, local, free, + if (!analyze_name(ste, scopes, name, flags, bound, local, free, global)) goto error; } + /* Populate global and bound sets to be passed to children. + */ if (ste->ste_type != ClassBlock) { + /* Add function locals to bound set */ if (ste->ste_type == FunctionBlock) { - if (PyDict_Update(newbound, local) < 0) + if (!PyNumber_InPlaceOr(newbound, local)) goto error; + Py_DECREF(newbound); } + /* Pass down previously bound symbols */ if (bound) { - if (PyDict_Update(newbound, bound) < 0) + if (!PyNumber_InPlaceOr(newbound, bound)) goto error; + Py_DECREF(newbound); } - if (PyDict_Update(newglobal, global) < 0) + /* Pass down known globals */ + if (!PyNumber_InPlaceOr(newglobal, global)) goto error; + Py_DECREF(newglobal); } /* Recursively call analyze_block() on each child block */ @@ -674,24 +708,28 @@ analyze_block(PySTEntryObject *ste, PyObject *bound, PyObject *free, entry = (PySTEntryObject*)c; if (!analyze_block(entry, newbound, newfree, newglobal)) goto error; + /* Check if any children have free variables */ if (entry->ste_free || entry->ste_child_free) ste->ste_child_free = 1; } - if (ste->ste_type == FunctionBlock && !analyze_cells(scope, newfree)) + /* Check if any local variables need to be converted to cell variables */ + if (ste->ste_type == FunctionBlock && !analyze_cells(scopes, newfree)) goto error; - if (!update_symbols(ste->ste_symbols, scope, bound, newfree, + /* Records the results of the analysis in the symbol table entry */ + if (!update_symbols(ste->ste_symbols, scopes, bound, newfree, ste->ste_type == ClassBlock)) goto error; if (!check_unoptimized(ste)) goto error; - if (PyDict_Update(free, newfree) < 0) + if (!PyNumber_InPlaceOr(free, newfree)) goto error; + Py_DECREF(free); success = 1; error: + Py_XDECREF(scopes); Py_XDECREF(local); - Py_XDECREF(scope); Py_XDECREF(newbound); Py_XDECREF(newglobal); Py_XDECREF(newfree); @@ -706,10 +744,10 @@ symtable_analyze(struct symtable *st) PyObject *free, *global; int r; - free = PyDict_New(); + free = PySet_New(NULL); if (!free) return 0; - global = PyDict_New(); + global = PySet_New(NULL); if (!global) { Py_DECREF(free); return 0; @@ -1200,14 +1238,16 @@ symtable_visit_expr(struct symtable *st, expr_ty e) case Set_kind: VISIT_SEQ(st, expr, e->v.Set.elts); break; + case GeneratorExp_kind: + if (!symtable_visit_genexp(st, e)) + return 0; + break; case ListComp_kind: - if (!symtable_new_tmpname(st)) + if (!symtable_visit_listcomp(st, e)) return 0; - VISIT(st, expr, e->v.ListComp.elt); - VISIT_SEQ(st, comprehension, e->v.ListComp.generators); break; - case GeneratorExp_kind: - if (!symtable_visit_genexp(st, e)) + case SetComp_kind: + if (!symtable_visit_setcomp(st, e)) return 0; break; case Yield_kind: @@ -1479,27 +1519,60 @@ symtable_visit_slice(struct symtable *st, slice_ty s) } static int -symtable_visit_genexp(struct symtable *st, expr_ty e) +symtable_handle_comprehension(struct symtable *st, expr_ty e, + identifier scope_name, + asdl_seq *generators, expr_ty elt) { + int is_generator = (e->kind == GeneratorExp_kind); + int needs_tmp = !is_generator; comprehension_ty outermost = ((comprehension_ty) - (asdl_seq_GET(e->v.GeneratorExp.generators, 0))); + asdl_seq_GET(generators, 0)); /* Outermost iterator is evaluated in current scope */ VISIT(st, expr, outermost->iter); - /* Create generator scope for the rest */ - if (!GET_IDENTIFIER(genexpr) || - !symtable_enter_block(st, genexpr, FunctionBlock, (void *)e, 0)) { + /* Create comprehension scope for the rest */ + if (!scope_name || + !symtable_enter_block(st, scope_name, FunctionBlock, (void *)e, 0)) { return 0; } - st->st_cur->ste_generator = 1; + st->st_cur->ste_generator = is_generator; /* Outermost iter is received as an argument */ if (!symtable_implicit_arg(st, 0)) { symtable_exit_block(st, (void *)e); return 0; } + /* Allocate temporary name if needed */ + if (needs_tmp && !symtable_new_tmpname(st)) { + symtable_exit_block(st, (void *)e); + return 0; + } VISIT_IN_BLOCK(st, expr, outermost->target, (void*)e); VISIT_SEQ_IN_BLOCK(st, expr, outermost->ifs, (void*)e); VISIT_SEQ_TAIL_IN_BLOCK(st, comprehension, - e->v.GeneratorExp.generators, 1, (void*)e); - VISIT_IN_BLOCK(st, expr, e->v.GeneratorExp.elt, (void*)e); + generators, 1, (void*)e); + VISIT_IN_BLOCK(st, expr, elt, (void*)e); return symtable_exit_block(st, (void *)e); } + +static int +symtable_visit_genexp(struct symtable *st, expr_ty e) +{ + return symtable_handle_comprehension(st, e, GET_IDENTIFIER(genexpr), + e->v.GeneratorExp.generators, + e->v.GeneratorExp.elt); +} + +static int +symtable_visit_listcomp(struct symtable *st, expr_ty e) +{ + return symtable_handle_comprehension(st, e, GET_IDENTIFIER(listcomp), + e->v.ListComp.generators, + e->v.ListComp.elt); +} + +static int +symtable_visit_setcomp(struct symtable *st, expr_ty e) +{ + return symtable_handle_comprehension(st, e, GET_IDENTIFIER(setcomp), + e->v.SetComp.generators, + e->v.SetComp.elt); +} |