/*

* This file includes functions to transform a concrete syntax tree (CST) to

* an abstract syntax tree (AST). The main function is PyAST_FromNode().

*

*/

#include "Python.h"

#include "Python-ast.h"

#include "grammar.h"

#include "node.h"

#include "pyarena.h"

#include "ast.h"

#include "token.h"

#include "parsetok.h"

#include "graminit.h"

#include <assert.h>

/* Data structure used internally */

struct compiling {

char *c_encoding; /* source encoding */

PyArena *c_arena; /* arena for allocating memeory */

const char *c_filename; /* filename */

};

static asdl_seq *seq_for_testlist(struct compiling *, const node *);

static expr_ty ast_for_expr(struct compiling *, const node *);

static stmt_ty ast_for_stmt(struct compiling *, const node *);

static asdl_seq *ast_for_suite(struct compiling *, const node *);

static asdl_seq *ast_for_exprlist(struct compiling *, const node *,

expr_context_ty);

static expr_ty ast_for_testlist(struct compiling *, const node *);

static expr_ty ast_for_testlist_gexp(struct compiling *, const node *);

/* Note different signature for ast_for_call */

static expr_ty ast_for_call(struct compiling *, const node *, expr_ty);

static PyObject *parsenumber(const char *);

static PyObject *parsestr(const char *s, const char *encoding);

static PyObject *parsestrplus(struct compiling *, const node *n);

#ifndef LINENO

#define LINENO(n) ((n)->n_lineno)

#endif

static identifier

new_identifier(const char* n, PyArena *arena) {

PyObject* id = PyString_InternFromString(n);

PyArena_AddPyObject(arena, id);

return id;

}

#define NEW_IDENTIFIER(n) new_identifier(STR(n), c->c_arena)

/* This routine provides an invalid object for the syntax error.

The outermost routine must unpack this error and create the

proper object. We do this so that we don't have to pass

the filename to everything function.

XXX Maybe we should just pass the filename...

*/

static int

ast_error(const node *n, const char *errstr)

{

PyObject *u = Py_BuildValue("zi", errstr, LINENO(n));

if (!u)

return 0;

PyErr_SetObject(PyExc_SyntaxError, u);

Py_DECREF(u);

return 0;

}

static void

ast_error_finish(const char *filename)

{

PyObject *type, *value, *tback, *errstr, *loc, *tmp;

long lineno;

assert(PyErr_Occurred());

if (!PyErr_ExceptionMatches(PyExc_SyntaxError))

return;

PyErr_Fetch(&type, &value, &tback);

errstr = PyTuple_GetItem(value, 0);

if (!errstr)

return;

Py_INCREF(errstr);

lineno = PyInt_AsLong(PyTuple_GetItem(value, 1));

if (lineno == -1) {

Py_DECREF(errstr);

return;

}

Py_DECREF(value);

loc = PyErr_ProgramText(filename, lineno);

if (!loc) {

Py_INCREF(Py_None);

loc = Py_None;

}

tmp = Py_BuildValue("(zlOO)", filename, lineno, Py_None, loc);

Py_DECREF(loc);

if (!tmp) {

Py_DECREF(errstr);

return;

}

value = PyTuple_Pack(2, errstr, tmp);

Py_DECREF(errstr);

Py_DECREF(tmp);

if (!value)

return;

PyErr_Restore(type, value, tback);

}

/* num_stmts() returns number of contained statements.

Use this routine to determine how big a sequence is needed for

the statements in a parse tree. Its raison d'etre is this bit of

grammar:

stmt: simple_stmt | compound_stmt

simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE

A simple_stmt can contain multiple small_stmt elements joined

by semicolons. If the arg is a simple_stmt, the number of

small_stmt elements is returned.

*/

static int

num_stmts(const node *n)

{

int i, l;

node *ch;

switch (TYPE(n)) {

case single_input:

if (TYPE(CHILD(n, 0)) == NEWLINE)

return 0;

else

return num_stmts(CHILD(n, 0));

case file_input:

l = 0;

for (i = 0; i < NCH(n); i++) {

ch = CHILD(n, i);

if (TYPE(ch) == stmt)

l += num_stmts(ch);

}

return l;

case stmt:

return num_stmts(CHILD(n, 0));

case compound_stmt:

return 1;

case simple_stmt:

return NCH(n) / 2; /* Divide by 2 to remove count of semi-colons */

case suite:

if (NCH(n) == 1)

return num_stmts(CHILD(n, 0));

else {

l = 0;

for (i = 2; i < (NCH(n) - 1); i++)

l += num_stmts(CHILD(n, i));

return l;

}

default: {

char buf[128];

sprintf(buf, "Non-statement found: %d %d\n",

TYPE(n), NCH(n));

Py_FatalError(buf);

}

}

assert(0);

return 0;

}

/* Transform the CST rooted at node * to the appropriate AST

*/

mod_ty

PyAST_FromNode(const node *n, PyCompilerFlags *flags, const char *filename,

PyArena *arena)

{

int i, j, k, num;

asdl_seq *stmts = NULL;

stmt_ty s;

node *ch;

struct compiling c;

if (flags && flags->cf_flags & PyCF_SOURCE_IS_UTF8) {

c.c_encoding = "utf-8";

if (TYPE(n) == encoding_decl) {

ast_error(n, "encoding declaration in Unicode string");

goto error;

}

} else if (TYPE(n) == encoding_decl) {

c.c_encoding = STR(n);

n = CHILD(n, 0);

} else {

c.c_encoding = NULL;

}

c.c_arena = arena;

c.c_filename = filename;

k = 0;

switch (TYPE(n)) {

case file_input:

stmts = asdl_seq_new(num_stmts(n), arena);

if (!stmts)

return NULL;

for (i = 0; i < NCH(n) - 1; i++) {

ch = CHILD(n, i);

if (TYPE(ch) == NEWLINE)

continue;

REQ(ch, stmt);

num = num_stmts(ch);

if (num == 1) {

s = ast_for_stmt(&c, ch);

if (!s)

goto error;

asdl_seq_SET(stmts, k++, s);

}

else {

ch = CHILD(ch, 0);

REQ(ch, simple_stmt);

for (j = 0; j < num; j++) {

s = ast_for_stmt(&c, CHILD(ch, j * 2));

if (!s)

goto error;

asdl_seq_SET(stmts, k++, s);

}

}

}

return Module(stmts, arena);

case eval_input: {

expr_ty testlist_ast;

/* XXX Why not gen_for here? */

testlist_ast = ast_for_testlist(&c, CHILD(n, 0));

if (!testlist_ast)

goto error;

return Expression(testlist_ast, arena);

}

case single_input:

if (TYPE(CHILD(n, 0)) == NEWLINE) {

stmts = asdl_seq_new(1, arena);

if (!stmts)

goto error;

asdl_seq_SET(stmts, 0, Pass(n->n_lineno, n->n_col_offset,

arena));

if (!asdl_seq_GET(stmts, 0))

goto error;

return Interactive(stmts, arena);

}

else {

n = CHILD(n, 0);

num = num_stmts(n);

stmts = asdl_seq_new(num, arena);

if (!stmts)

goto error;

if (num == 1) {

s = ast_for_stmt(&c, n);

if (!s)

goto error;

asdl_seq_SET(stmts, 0, s);

}

else {

/* Only a simple_stmt can contain multiple statements. */

REQ(n, simple_stmt);

for (i = 0; i < NCH(n); i += 2) {

if (TYPE(CHILD(n, i)) == NEWLINE)

break;

s = ast_for_stmt(&c, CHILD(n, i));

if (!s)

goto error;

asdl_seq_SET(stmts, i / 2, s);

}

}

return Interactive(stmts, arena);

}

default:

PyErr_Format(PyExc_SystemError,

"invalid node %d for PyAST_FromNode", TYPE(n));

goto error;

}

error:

ast_error_finish(filename);

return NULL;

}

/* Return the AST repr. of the operator represented as syntax (|, ^, etc.)

*/

static operator_ty

get_operator(const node *n)

{

switch (TYPE(n)) {

case VBAR:

return BitOr;

case CIRCUMFLEX:

return BitXor;

case AMPER:

return BitAnd;

case LEFTSHIFT:

return LShift;

case RIGHTSHIFT:

return RShift;

case PLUS:

return Add;

case MINUS:

return Sub;

case STAR:

return Mult;

case SLASH:

return Div;

case DOUBLESLASH:

return FloorDiv;

case PERCENT:

return Mod;

default:

return (operator_ty)0;

}

}

/* Set the context ctx for expr_ty e, recursively traversing e.

Only sets context for expr kinds that "can appear in assignment context"

(according to ../Parser/Python.asdl). For other expr kinds, it sets

an appropriate syntax error and returns false.

*/

static int

set_context(expr_ty e, expr_context_ty ctx, const node *n)

{

asdl_seq *s = NULL;

/* If a particular expression type can't be used for assign / delete,

set expr_name to its name and an error message will be generated.

*/

const char* expr_name = NULL;

/* The ast defines augmented store and load contexts, but the

implementation here doesn't actually use them. The code may be

a little more complex than necessary as a result. It also means

that expressions in an augmented assignment have a Store context.

Consider restructuring so that augmented assignment uses

set_context(), too.

*/

assert(ctx != AugStore && ctx != AugLoad);

switch (e->kind) {

case Attribute_kind:

if (ctx == Store &&

!strcmp(PyString_AS_STRING(e->v.Attribute.attr), "None")) {

return ast_error(n, "assignment to None");

}

e->v.Attribute.ctx = ctx;

break;

case Subscript_kind:

e->v.Subscript.ctx = ctx;

break;

case Name_kind:

if (ctx == Store &&

!strcmp(PyString_AS_STRING(e->v.Name.id), "None")) {

return ast_error(n, "assignment to None");

}

e->v.Name.ctx = ctx;

break;

case List_kind:

e->v.List.ctx = ctx;

s = e->v.List.elts;

break;

case Tuple_kind:

if (asdl_seq_LEN(e->v.Tuple.elts) == 0)

return ast_error(n, "can't assign to ()");

e->v.Tuple.ctx = ctx;

s = e->v.Tuple.elts;

break;

case Lambda_kind:

expr_name = "lambda";

break;

case Call_kind:

expr_name = "function call";

break;

case BoolOp_kind:

case BinOp_kind:

case UnaryOp_kind:

expr_name = "operator";

break;

case GeneratorExp_kind:

expr_name = "generator expression";

break;

case Yield_kind:

expr_name = "yield expression";

break;

case ListComp_kind:

expr_name = "list comprehension";

break;

case Dict_kind:

case Num_kind:

case Str_kind:

expr_name = "literal";

break;

case Compare_kind:

expr_name = "comparison";

break;

case Repr_kind:

expr_name = "repr";

break;

case IfExp_kind:

expr_name = "conditional expression";

break;

default:

PyErr_Format(PyExc_SystemError,

"unexpected expression in assignment %d (line %d)",

e->kind, e->lineno);

return 0;

}

/* Check for error string set by switch */

if (expr_name) {

char buf[300];

PyOS_snprintf(buf, sizeof(buf),

"can't %s %s",

ctx == Store ? "assign to" : "delete",

expr_name);

return ast_error(n, buf);

}

/* If the LHS is a list or tuple, we need to set the assignment

context for all the contained elements.

*/

if (s) {

int i;

for (i = 0; i < asdl_seq_LEN(s); i++) {

if (!set_context((expr_ty)asdl_seq_GET(s, i), ctx, n))

return 0;

}

}

return 1;

}

static operator_ty

ast_for_augassign(const node *n)

{

REQ(n, augassign);

n = CHILD(n, 0);

switch (STR(n)[0]) {

case '+':

return Add;

case '-':

return Sub;

case '/':

if (STR(n)[1] == '/')

return FloorDiv;

else

return Div;

case '%':

return Mod;

case '<':

return LShift;

case '>':

return RShift;

case '&':

return BitAnd;

case '^':

return BitXor;

case '|':

return BitOr;

case '*':

if (STR(n)[1] == '*')

return Pow;

else

return Mult;

default:

PyErr_Format(PyExc_SystemError, "invalid augassign: %s", STR(n));

return (operator_ty)0;

}

}

static cmpop_ty

ast_for_comp_op(const node *n)

{

/* comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'

|'is' 'not'

*/

REQ(n, comp_op);

if (NCH(n) == 1) {

n = CHILD(n, 0);

switch (TYPE(n)) {

case LESS:

return Lt;

case GREATER:

return Gt;

case EQEQUAL: /* == */

return Eq;

case LESSEQUAL:

return LtE;

case GREATEREQUAL:

return GtE;

case NOTEQUAL:

return NotEq;

case NAME:

if (strcmp(STR(n), "in") == 0)

return In;

if (strcmp(STR(n), "is") == 0)

return Is;

default:

PyErr_Format(PyExc_SystemError, "invalid comp_op: %s",

STR(n));

return (cmpop_ty)0;

}

}

else if (NCH(n) == 2) {

/* handle "not in" and "is not" */

switch (TYPE(CHILD(n, 0))) {

case NAME:

if (strcmp(STR(CHILD(n, 1)), "in") == 0)

return NotIn;

if (strcmp(STR(CHILD(n, 0)), "is") == 0)

return IsNot;

default:

PyErr_Format(PyExc_SystemError, "invalid comp_op: %s %s",

STR(CHILD(n, 0)), STR(CHILD(n, 1)));

return (cmpop_ty)0;

}

}

PyErr_Format(PyExc_SystemError, "invalid comp_op: has %d children",

NCH(n));

return (cmpop_ty)0;

}

static asdl_seq *

seq_for_testlist(struct compiling *c, const node *n)

{

/* testlist: test (',' test)* [','] */

asdl_seq *seq;

expr_ty expression;

int i;

assert(TYPE(n) == testlist ||

TYPE(n) == listmaker ||

TYPE(n) == testlist_gexp ||

TYPE(n) == testlist_safe ||

TYPE(n) == testlist1);

seq = asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);

if (!seq)

return NULL;

for (i = 0; i < NCH(n); i += 2) {

assert(TYPE(CHILD(n, i)) == test || TYPE(CHILD(n, i)) == old_test);

expression = ast_for_expr(c, CHILD(n, i));

if (!expression)

return NULL;

assert(i / 2 < seq->size);

asdl_seq_SET(seq, i / 2, expression);

}

return seq;

}

static expr_ty

compiler_complex_args(struct compiling *c, const node *n)

{

int i, len = (NCH(n) + 1) / 2;

expr_ty result;

asdl_seq *args = asdl_seq_new(len, c->c_arena);

if (!args)

return NULL;

/* fpdef: NAME | '(' fplist ')'

fplist: fpdef (',' fpdef)* [',']

*/

REQ(n, fplist);

for (i = 0; i < len; i++) {

const node *fpdef_node = CHILD(n, 2*i);

const node *child;

expr_ty arg;

set_name:

/* fpdef_node is either a NAME or an fplist */

child = CHILD(fpdef_node, 0);

if (TYPE(child) == NAME) {

if (!strcmp(STR(child), "None")) {

ast_error(child, "assignment to None");

return NULL;

}

arg = Name(NEW_IDENTIFIER(child), Store, LINENO(child),

child->n_col_offset, c->c_arena);

}

else {

assert(TYPE(fpdef_node) == fpdef);

/* fpdef_node[0] is not a name, so it must be '(', get CHILD[1] */

child = CHILD(fpdef_node, 1);

assert(TYPE(child) == fplist);

/* NCH == 1 means we have (x), we need to elide the extra parens */

if (NCH(child) == 1) {

fpdef_node = CHILD(child, 0);

assert(TYPE(fpdef_node) == fpdef);

goto set_name;

}

arg = compiler_complex_args(c, child);

}

asdl_seq_SET(args, i, arg);

}

result = Tuple(args, Store, LINENO(n), n->n_col_offset, c->c_arena);

if (!set_context(result, Store, n))

return NULL;

return result;

}

/* Create AST for argument list. */

static arguments_ty

ast_for_arguments(struct compiling *c, const node *n)

{

/* parameters: '(' [varargslist] ')'

varargslist: (fpdef ['=' test] ',')* ('*' NAME [',' '**' NAME]

| '**' NAME) | fpdef ['=' test] (',' fpdef ['=' test])* [',']

*/

int i, j, k, n_args = 0, n_defaults = 0, found_default = 0;

asdl_seq *args, *defaults;

identifier vararg = NULL, kwarg = NULL;

node *ch;

if (TYPE(n) == parameters) {

if (NCH(n) == 2) /* () as argument list */

return arguments(NULL, NULL, NULL, NULL, c->c_arena);

n = CHILD(n, 1);

}

REQ(n, varargslist);

/* first count the number of normal args & defaults */

for (i = 0; i < NCH(n); i++) {

ch = CHILD(n, i);

if (TYPE(ch) == fpdef)

n_args++;

if (TYPE(ch) == EQUAL)

n_defaults++;

}

args = (n_args ? asdl_seq_new(n_args, c->c_arena) : NULL);

if (!args && n_args)

return NULL; /* Don't need to goto error; no objects allocated */

defaults = (n_defaults ? asdl_seq_new(n_defaults, c->c_arena) : NULL);

if (!defaults && n_defaults)

return NULL; /* Don't need to goto error; no objects allocated */

/* fpdef: NAME | '(' fplist ')'

fplist: fpdef (',' fpdef)* [',']

*/

i = 0;

j = 0; /* index for defaults */

k = 0; /* index for args */

while (i < NCH(n)) {

ch = CHILD(n, i);

switch (TYPE(ch)) {

case fpdef:

handle_fpdef:

/* XXX Need to worry about checking if TYPE(CHILD(n, i+1)) is

anything other than EQUAL or a comma? */

/* XXX Should NCH(n) check be made a separate check? */

if (i + 1 < NCH(n) && TYPE(CHILD(n, i + 1)) == EQUAL) {

expr_ty expression = ast_for_expr(c, CHILD(n, i + 2));

if (!expression)

goto error;

assert(defaults != NULL);

asdl_seq_SET(defaults, j++, expression);

i += 2;

found_default = 1;

}

else if (found_default) {

ast_error(n,

"non-default argument follows default argument");

goto error;

}

if (NCH(ch) == 3) {

ch = CHILD(ch, 1);

/* def foo((x)): is not complex, special case. */

if (NCH(ch) != 1) {

/* We have complex arguments, setup for unpacking. */

asdl_seq_SET(args, k++, compiler_complex_args(c, ch));

if (!asdl_seq_GET(args, k-1))

goto error;

} else {

/* def foo((x)): setup for checking NAME below. */

/* Loop because there can be many parens and tuple

unpacking mixed in. */

ch = CHILD(ch, 0);

assert(TYPE(ch) == fpdef);

goto handle_fpdef;

}

}

if (TYPE(CHILD(ch, 0)) == NAME) {

expr_ty name;

if (!strcmp(STR(CHILD(ch, 0)), "None")) {

ast_error(CHILD(ch, 0), "assignment to None");

goto error;

}

name = Name(NEW_IDENTIFIER(CHILD(ch, 0)),

Param, LINENO(ch), ch->n_col_offset,

c->c_arena);

if (!name)

goto error;

asdl_seq_SET(args, k++, name);

}

i += 2; /* the name and the comma */

break;

case STAR:

if (!strcmp(STR(CHILD(n, i+1)), "None")) {

ast_error(CHILD(n, i+1), "assignment to None");

goto error;

}

vararg = NEW_IDENTIFIER(CHILD(n, i+1));

i += 3;

break;

case DOUBLESTAR:

if (!strcmp(STR(CHILD(n, i+1)), "None")) {

ast_error(CHILD(n, i+1), "assignment to None");

goto error;

}

kwarg = NEW_IDENTIFIER(CHILD(n, i+1));

i += 3;

break;

default:

PyErr_Format(PyExc_SystemError,

"unexpected node in varargslist: %d @ %d",

TYPE(ch), i);

goto error;

}

}

return arguments(args, vararg, kwarg, defaults, c->c_arena);

error:

Py_XDECREF(vararg);

Py_XDECREF(kwarg);

return NULL;

}

static expr_ty

ast_for_dotted_name(struct compiling *c, const node *n)

{

expr_ty e;

identifier id;

int lineno, col_offset;

int i;

REQ(n, dotted_name);

lineno = LINENO(n);

col_offset = n->n_col_offset;

id = NEW_IDENTIFIER(CHILD(n, 0));

if (!id)

return NULL;

e = Name(id, Load, lineno, col_offset, c->c_arena);

if (!e)

return NULL;

for (i = 2; i < NCH(n); i+=2) {

id = NEW_IDENTIFIER(CHILD(n, i));

if (!id)

return NULL;

e = Attribute(e, id, Load, lineno, col_offset, c->c_arena);

if (!e)

return NULL;

}

return e;

}

static expr_ty

ast_for_decorator(struct compiling *c, const node *n)

{

/* decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE */

expr_ty d = NULL;

expr_ty name_expr;

REQ(n, decorator);

REQ(CHILD(n, 0), AT);

REQ(RCHILD(n, -1), NEWLINE);

name_expr = ast_for_dotted_name(c, CHILD(n, 1));

if (!name_expr)

return NULL;

if (NCH(n) == 3) { /* No arguments */

d = name_expr;

name_expr = NULL;

}

else if (NCH(n) == 5) { /* Call with no arguments */

d = Call(name_expr, NULL, NULL, NULL, NULL, LINENO(n),

n->n_col_offset, c->c_arena);

if (!d)

return NULL;

name_expr = NULL;

}

else {

d = ast_for_call(c, CHILD(n, 3), name_expr);

if (!d)

return NULL;

name_expr = NULL;

}

return d;

}

static asdl_seq*

ast_for_decorators(struct compiling *c, const node *n)

{

asdl_seq* decorator_seq;

expr_ty d;

int i;

REQ(n, decorators);

decorator_seq = asdl_seq_new(NCH(n), c->c_arena);

if (!decorator_seq)

return NULL;

for (i = 0; i < NCH(n); i++) {

d = ast_for_decorator(c, CHILD(n, i));

if (!d)

return NULL;

asdl_seq_SET(decorator_seq, i, d);

}

return decorator_seq;

}

static stmt_ty

ast_for_funcdef(struct compiling *c, const node *n)

{

/* funcdef: 'def' [decorators] NAME parameters ':' suite */

identifier name;

arguments_ty args;

asdl_seq *body;

asdl_seq *decorator_seq = NULL;

int name_i;

REQ(n, funcdef);

if (NCH(n) == 6) { /* decorators are present */

decorator_seq = ast_for_decorators(c, CHILD(n, 0));

if (!decorator_seq)

return NULL;

name_i = 2;

}

else {

name_i = 1;

}

name = NEW_IDENTIFIER(CHILD(n, name_i));

if (!name)

return NULL;

else if (!strcmp(STR(CHILD(n, name_i)), "None")) {

ast_error(CHILD(n, name_i), "assignment to None");

return NULL;

}

args = ast_for_arguments(c, CHILD(n, name_i + 1));

if (!args)

return NULL;

body = ast_for_suite(c, CHILD(n, name_i + 3));

if (!body)

return NULL;

return FunctionDef(name, args, body, decorator_seq, LINENO(n),

n->n_col_offset, c->c_arena);

}

static expr_ty

ast_for_lambdef(struct compiling *c, const node *n)

{

/* lambdef: 'lambda' [varargslist] ':' test */

arguments_ty args;

expr_ty expression;

if (NCH(n) == 3) {

args = arguments(NULL, NULL, NULL, NULL, c->c_arena);

if (!args)

return NULL;

expression = ast_for_expr(c, CHILD(n, 2));

if (!expression)

return NULL;

}

else {

args = ast_for_arguments(c, CHILD(n, 1));

if (!args)

return NULL;

expression = ast_for_expr(c, CHILD(n, 3));

if (!expression)

return NULL;

}

return Lambda(args, expression, LINENO(n), n->n_col_offset, c->c_arena);

}

static expr_ty

ast_for_ifexpr(struct compiling *c, const node *n)

{

/* test: or_test 'if' or_test 'else' test */

expr_ty expression, body, orelse;

assert(NCH(n) == 5);

body = ast_for_expr(c, CHILD(n, 0));

if (!body)

return NULL;

expression = ast_for_expr(c, CHILD(n, 2));

if (!expression)

return NULL;

orelse = ast_for_expr(c, CHILD(n, 4));

if (!orelse)

return NULL;

return IfExp(expression, body, orelse, LINENO(n), n->n_col_offset,

c->c_arena);

}

/* XXX(nnorwitz): the listcomp and genexpr code should be refactored

so there is only a single version. Possibly for loops can also re-use

the code.

*/

/* Count the number of 'for' loop in a list comprehension.

Helper for ast_for_listcomp().

*/

static int

count_list_fors(const node *n)

{

int n_fors = 0;

node *ch = CHILD(n, 1);

count_list_for:

n_fors++;

REQ(ch, list_for);

if (NCH(ch) == 5)

ch = CHILD(ch, 4);

else

return n_fors;

count_list_iter:

REQ(ch, list_iter);

ch = CHILD(ch, 0);

if (TYPE(ch) == list_for)

goto count_list_for;

else if (TYPE(ch) == list_if) {

if (NCH(ch) == 3) {

ch = CHILD(ch, 2);

goto count_list_iter;

}

else

return n_fors;

}

/* Should never be reached */

PyErr_SetString(PyExc_SystemError, "logic error in count_list_fors");

return -1;

}

/* Count the number of 'if' statements in a list comprehension.

Helper for ast_for_listcomp().

*/

static int

count_list_ifs(const node *n)

{

int n_ifs = 0;

count_list_iter:

REQ(n, list_iter);

if (TYPE(CHILD(n, 0)) == list_for)

return n_ifs;

n = CHILD(n, 0);

REQ(n, list_if);

n_ifs++;

if (NCH(n) == 2)

return n_ifs;

n = CHILD(n, 2);

goto count_list_iter;

}

static expr_ty

ast_for_listcomp(struct compiling *c, const node *n)

{

/* listmaker: test ( list_for | (',' test)* [','] )

list_for: 'for' exprlist 'in' testlist_safe [list_iter]

list_iter: list_for | list_if

list_if: 'if' test [list_iter]

testlist_safe: test [(',' test)+ [',']]

*/

expr_ty elt;

asdl_seq *listcomps;

int i, n_fors;

node *ch;

REQ(n, listmaker);

assert(NCH(n) > 1);

elt = ast_for_expr(c, CHILD(n, 0));

if (!elt)