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
17 namespace 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]...
24 constexpr auto label{space >> digitString64 / spaceCheck};
25
26 template <typename PA>
unterminatedStatement(const PA & p)27 inline constexpr auto unterminatedStatement(const PA &p) {
28 return skipStuffBeforeStatement >>
29 sourced(construct<Statement<typename PA::resultType>>(
30 maybe(label), space >> p));
31 }
32
33 constexpr auto endOfLine{
34 "\n"_ch >> ok || fail("expected end of line"_err_en_US)};
35
36 constexpr auto semicolons{";"_ch >> skipMany(";"_tok) / space / maybe("\n"_ch)};
37 constexpr auto endOfStmt{
38 space >> withMessage("expected end of statement"_err_en_US,
39 semicolons || endOfLine)};
40 constexpr auto forceEndOfStmt{recovery(endOfStmt, SkipPast<'\n'>{})};
41
statement(const PA & p)42 template <typename PA> inline constexpr auto statement(const PA &p) {
43 return unterminatedStatement(p) / endOfStmt;
44 }
45
46 // unlabeledStatement() is basically statement() for those few situations
47 // in Fortran where a statement cannot have a label.
unlabeledStatement(const PA & p)48 template <typename PA> inline constexpr auto unlabeledStatement(const PA &p) {
49 return space >>
50 sourced(construct<UnlabeledStatement<typename PA::resultType>>(p));
51 }
52
53 // This unambiguousStatement() variant of statement() provides better error
54 // recovery for contexts containing statements that might have trailing
55 // garbage, but it must be used only when no instance of the statement in
56 // question could also be a legal prefix of some other statement that might
57 // be valid at that point. It only makes sense to use this within "some()"
58 // or "many()" so as to not end the list of statements.
unambiguousStatement(const PA & p)59 template <typename PA> inline constexpr auto unambiguousStatement(const PA &p) {
60 return unterminatedStatement(p) / forceEndOfStmt;
61 }
62
63 constexpr auto ignoredStatementPrefix{
64 skipStuffBeforeStatement >> maybe(label) >> maybe(name / ":") >> space};
65
66 // Error recovery within a statement() call: skip *to* the end of the line,
67 // unless at an END or CONTAINS statement.
68 constexpr auto inStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
69 SkipTo<'\n'>{} >> construct<ErrorRecovery>()};
70
71 // Error recovery within statement sequences: skip *past* the end of the line,
72 // but not over an END or CONTAINS statement.
73 constexpr auto skipStmtErrorRecovery{!"END"_tok >> !"CONTAINS"_tok >>
74 SkipPast<'\n'>{} >> construct<ErrorRecovery>()};
75
76 // Error recovery across statements: skip the line, unless it looks
77 // like it might end the containing construct.
78 constexpr auto stmtErrorRecoveryStart{ignoredStatementPrefix};
79 constexpr auto skipBadLine{SkipPast<'\n'>{} >> construct<ErrorRecovery>()};
80 constexpr auto executionPartErrorRecovery{stmtErrorRecoveryStart >>
81 !"END"_tok >> !"CONTAINS"_tok >> !"ELSE"_tok >> !"CASE"_tok >>
82 !"TYPE IS"_tok >> !"CLASS"_tok >> !"RANK"_tok >>
83 !("!$ACC "_sptok >> "END"_tok) >>
84 !("!$OMP "_sptok >> ("END"_tok || "SECTION"_id)) >> skipBadLine};
85
86 // END statement error recovery
87 constexpr auto missingOptionalName{pure<std::optional<Name>>()};
88 constexpr auto noNameEnd{"END" >> missingOptionalName};
89 constexpr auto atEndOfStmt{space >>
90 withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
91 constexpr auto bareEnd{noNameEnd / recovery(atEndOfStmt, SkipTo<'\n'>{})};
92
93 constexpr auto endStmtErrorRecovery{
94 ("END"_tok >> SkipTo<'\n'>{} || ok) >> missingOptionalName};
95
96 constexpr auto progUnitEndStmtErrorRecovery{
97 (many(!"END"_tok >> SkipPast<'\n'>{}) >>
98 ("END"_tok >> SkipTo<'\n'>{} || consumedAllInput)) >>
99 missingOptionalName};
100 } // namespace Fortran::parser
101 #endif // FORTRAN_PARSER_STMT_PARSER_H_
102