1//===-- lib/Parser/stmt-parser.h --------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef FORTRAN_PARSER_STMT_PARSER_H_
10#define FORTRAN_PARSER_STMT_PARSER_H_
11
12// Basic parsing of statements.
13
14#include "basic-parsers.h"
15#include "token-parsers.h"
16
17namespace Fortran::parser {
18
19// statement(p) parses Statement<P> for some statement type P that is the
20// result type of the argument parser p, while also handling labels and
21// end-of-statement markers.
22
23// R611 label -> digit [digit]...
24constexpr auto label{space >> digitString64 / spaceCheck};
25
26template <typename PA>
27inline constexpr auto unterminatedStatement(const PA &p) {
28 return skipStuffBeforeStatement >>
29 sourced(construct<Statement<typename PA::resultType>>(
30 maybe(label), space >> p));
31}
32
33constexpr auto atEndOfStmt{space >>
34 withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
35constexpr auto checkEndOfKnownStmt{recovery(atEndOfStmt, SkipTo<'\n'>{})};
36
37constexpr auto endOfLine{
38 "\n"_ch >> ok || fail("expected end of line"_err_en_US)};
39
40constexpr auto semicolons{";"_ch >> skipMany(";"_tok) / space / maybe("\n"_ch)};
41constexpr auto endOfStmt{
42 space >> withMessage("expected end of statement"_err_en_US,
43 semicolons || endOfLine)};
44constexpr auto forceEndOfStmt{recovery(endOfStmt, SkipPast<'\n'>{})};
45
46template <typename PA> inline constexpr auto statement(const PA &p) {
47 return unterminatedStatement(p) / endOfStmt;
48}
49
50// unlabeledStatement() is basically statement() for those few situations
51// in Fortran where a statement cannot have a label.
52template <typename PA> inline constexpr auto unlabeledStatement(const PA &p) {
53 return space >>
54 sourced(construct<UnlabeledStatement<typename PA::resultType>>(p));
55}
56
57// This unambiguousStatement() variant of statement() provides better error
58// recovery for contexts containing statements that might have trailing
59// garbage, but it must be used only when no instance of the statement in
60// question could also be a legal prefix of some other statement that might
61// be valid at that point. It only makes sense to use this within "some()"
62// or "many()" so as to not end the list of statements.
63template <typename PA> inline constexpr auto unambiguousStatement(const PA &p) {
64 return unterminatedStatement(p) / forceEndOfStmt;
65}
66
67constexpr auto ignoredStatementPrefix{
68 skipStuffBeforeStatement >> maybe(label) >> maybe(name / ":") >> space};
69
70// Error recovery within a statement() call: skip *to* the end of the line,
71// unless at an END or CONTAINS statement.
72constexpr auto inStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
73 SkipTo<'\n'>{} >> construct<ErrorRecovery>()};
74
75// Error recovery within statement sequences: skip *past* the end of the line,
76// but not over an END or CONTAINS statement.
77constexpr auto skipStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
78 SkipPast<'\n'>{} >> construct<ErrorRecovery>()};
79
80// Error recovery across statements: skip the line, unless it looks
81// like it might end the containing construct.
82constexpr auto stmtErrorRecoveryStart{ignoredStatementPrefix};
83constexpr auto skipBadLine{SkipPast<'\n'>{} >> construct<ErrorRecovery>()};
84constexpr auto executionPartErrorRecovery{stmtErrorRecoveryStart >>
85 !"END"_tok >> !"CONTAINS"_tok >> !"ELSE"_tok >> !"CASE"_tok >>
86 !"TYPE IS"_tok >> !"CLASS"_tok >> !"RANK"_tok >>
87 !("!$ACC "_sptok >> "END"_tok) >>
88 !("!$OMP "_sptok >> ("END"_tok || "SECTION"_id)) >> skipBadLine};
89
90// END statement error recovery
91constexpr auto missingOptionalName{pure<std::optional<Name>>()};
92constexpr auto noNameEnd{"END" >> missingOptionalName};
93
94// For unrecognizable construct END statements. Be sure to not consume
95// a program unit's END statement.
96constexpr auto progUnitEndStmt{
97 "END" >> (lookAhead("\n"_ch) || "SUBROUTINE"_tok || "FUNCTION"_tok ||
98 "PROCEDURE"_tok || "MODULE"_tok || "SUBMODULE"_tok ||
99 "PROGRAM"_tok || "BLOCK DATA"_tok)};
100constexpr auto constructEndStmtErrorRecovery{
101 !progUnitEndStmt >> ("END"_tok >> SkipTo<'\n'>{} || ok)};
102constexpr auto namedConstructEndStmtErrorRecovery{
103 constructEndStmtErrorRecovery >> missingOptionalName};
104
105constexpr auto progUnitEndStmtErrorRecovery{
106 (many(!"END"_tok >> SkipPast<'\n'>{}) >>
107 ("END"_tok >> SkipTo<'\n'>{} || consumedAllInput)) >>
108 missingOptionalName};
109
110constexpr auto beginDirective{skipStuffBeforeStatement >> "!"_ch};
111constexpr auto endDirective{space >> endOfLine};
112
113} // namespace Fortran::parser
114#endif // FORTRAN_PARSER_STMT_PARSER_H_
115

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source code of flang/lib/Parser/stmt-parser.h