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py/compile: Implement PEP 526, syntax for variable annotations.
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This addition to the grammar was introduced in Python 3.6.  It allows
annotating the type of a varilable, like:

    x: int = 123
    s: str

The implementation in this commit is quite simple and just ignores the
annotation (the int and str bits above).  The reason to implement this is
to allow Python 3.6+ code that uses this feature to compile under
MicroPython without change, and for users to use type checkers.

In the future viper could use this syntax as a way to give types to
variables, which is currently done in a bit of an ad-hoc way, eg
x = int(123).  And this syntax could potentially be used in the inline
assembler to define labels in an way that's easier to read.
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@dpgeorge
dpgeorge committed Jun 16, 2020
1 parent 131b0de commit f2e267d
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Showing 2 changed files with 29 additions and 10 deletions.
31 changes: 24 additions & 7 deletions py/compile.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1981,7 +1981,8 @@ STATIC void compile_async_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
#endif

STATIC void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
if (MP_PARSE_NODE_IS_NULL(pns->nodes[1])) {
mp_parse_node_t pn_rhs = pns->nodes[1];
if (MP_PARSE_NODE_IS_NULL(pn_rhs)) {
if (comp->is_repl && comp->scope_cur->kind == SCOPE_MODULE) {
// for REPL, evaluate then print the expression
compile_load_id(comp, MP_QSTR___repl_print__);
Expand All @@ -1999,10 +2000,26 @@ STATIC void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
EMIT(pop_top); // discard last result since this is a statement and leaves nothing on the stack
}
}
} else if (MP_PARSE_NODE_IS_STRUCT(pns->nodes[1])) {
mp_parse_node_struct_t *pns1 = (mp_parse_node_struct_t *)pns->nodes[1];
} else if (MP_PARSE_NODE_IS_STRUCT(pn_rhs)) {
mp_parse_node_struct_t *pns1 = (mp_parse_node_struct_t *)pn_rhs;
int kind = MP_PARSE_NODE_STRUCT_KIND(pns1);
if (kind == PN_expr_stmt_augassign) {
if (kind == PN_annassign) {
// the annotation is in pns1->nodes[0] and is ignored
if (MP_PARSE_NODE_IS_NULL(pns1->nodes[1])) {
// an annotation of the form "x: y"
// inside a function this declares "x" as a local
if (comp->scope_cur->kind == SCOPE_FUNCTION) {
if (MP_PARSE_NODE_IS_ID(pns->nodes[0])) {
qstr lhs = MP_PARSE_NODE_LEAF_ARG(pns->nodes[0]);
scope_find_or_add_id(comp->scope_cur, lhs, ID_INFO_KIND_LOCAL);
}
}
} else {
// an assigned annotation of the form "x: y = z"
pn_rhs = pns1->nodes[1];
goto plain_assign;
}
} else if (kind == PN_expr_stmt_augassign) {
c_assign(comp, pns->nodes[0], ASSIGN_AUG_LOAD); // lhs load for aug assign
compile_node(comp, pns1->nodes[1]); // rhs
assert(MP_PARSE_NODE_IS_TOKEN(pns1->nodes[0]));
Expand All @@ -2027,10 +2044,10 @@ STATIC void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
} else {
plain_assign:
#if MICROPY_COMP_DOUBLE_TUPLE_ASSIGN
if (MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[1], PN_testlist_star_expr)
if (MP_PARSE_NODE_IS_STRUCT_KIND(pn_rhs, PN_testlist_star_expr)
&& MP_PARSE_NODE_IS_STRUCT_KIND(pns->nodes[0], PN_testlist_star_expr)) {
mp_parse_node_struct_t *pns0 = (mp_parse_node_struct_t *)pns->nodes[0];
pns1 = (mp_parse_node_struct_t *)pns->nodes[1];
pns1 = (mp_parse_node_struct_t *)pn_rhs;
uint32_t n_pns0 = MP_PARSE_NODE_STRUCT_NUM_NODES(pns0);
// Can only optimise a tuple-to-tuple assignment when all of the following hold:
// - equal number of items in LHS and RHS tuples
Expand Down Expand Up @@ -2070,7 +2087,7 @@ STATIC void compile_expr_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
}
#endif

compile_node(comp, pns->nodes[1]); // rhs
compile_node(comp, pn_rhs); // rhs
c_assign(comp, pns->nodes[0], ASSIGN_STORE); // lhs store
}
} else {
Expand Down
8 changes: 5 additions & 3 deletions py/grammar.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -98,20 +98,22 @@ DEF_RULE_NC(simple_stmt, and_ident(2), rule(simple_stmt_2), tok(NEWLINE))
DEF_RULE(simple_stmt_2, c(generic_all_nodes), list_with_end, rule(small_stmt), tok(DEL_SEMICOLON))

// small_stmt: expr_stmt | del_stmt | pass_stmt | flow_stmt | import_stmt | global_stmt | nonlocal_stmt | assert_stmt
// expr_stmt: testlist_star_expr (augassign (yield_expr|testlist) | ('=' (yield_expr|testlist_star_expr))*)
// expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) | ('=' (yield_expr|testlist_star_expr))*)
// testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
// annassign: ':' test ['=' (yield_expr|testlist_star_expr)]
// augassign: '+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' | '<<=' | '>>=' | '**=' | '//='
// # For normal assignments, additional restrictions enforced by the interpreter
// # For normal and annotated assignments, additional restrictions enforced by the interpreter

DEF_RULE_NC(small_stmt, or(8), rule(del_stmt), rule(pass_stmt), rule(flow_stmt), rule(import_stmt), rule(global_stmt), rule(nonlocal_stmt), rule(assert_stmt), rule(expr_stmt))
DEF_RULE(expr_stmt, c(expr_stmt), and(2), rule(testlist_star_expr), opt_rule(expr_stmt_2))
DEF_RULE_NC(expr_stmt_2, or(2), rule(expr_stmt_augassign), rule(expr_stmt_assign_list))
DEF_RULE_NC(expr_stmt_2, or(3), rule(annassign), rule(expr_stmt_augassign), rule(expr_stmt_assign_list))
DEF_RULE_NC(expr_stmt_augassign, and_ident(2), rule(augassign), rule(expr_stmt_6))
DEF_RULE_NC(expr_stmt_assign_list, one_or_more, rule(expr_stmt_assign))
DEF_RULE_NC(expr_stmt_assign, and_ident(2), tok(DEL_EQUAL), rule(expr_stmt_6))
DEF_RULE_NC(expr_stmt_6, or(2), rule(yield_expr), rule(testlist_star_expr))
DEF_RULE(testlist_star_expr, c(generic_tuple), list_with_end, rule(testlist_star_expr_2), tok(DEL_COMMA))
DEF_RULE_NC(testlist_star_expr_2, or(2), rule(star_expr), rule(test))
DEF_RULE_NC(annassign, and(3), tok(DEL_COLON), rule(test), opt_rule(expr_stmt_assign))
DEF_RULE_NC(augassign, or(13), tok(DEL_PLUS_EQUAL), tok(DEL_MINUS_EQUAL), tok(DEL_STAR_EQUAL), tok(DEL_AT_EQUAL), tok(DEL_SLASH_EQUAL), tok(DEL_PERCENT_EQUAL), tok(DEL_AMPERSAND_EQUAL), tok(DEL_PIPE_EQUAL), tok(DEL_CARET_EQUAL), tok(DEL_DBL_LESS_EQUAL), tok(DEL_DBL_MORE_EQUAL), tok(DEL_DBL_STAR_EQUAL), tok(DEL_DBL_SLASH_EQUAL))

// del_stmt: 'del' exprlist
Expand Down

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