1 //===-- CommandObjectDWIMPrint.cpp ------------------------------*- 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 #include "CommandObjectDWIMPrint.h"
10
11 #include "lldb/Core/ValueObject.h"
12 #include "lldb/DataFormatters/DumpValueObjectOptions.h"
13 #include "lldb/Expression/ExpressionVariable.h"
14 #include "lldb/Expression/UserExpression.h"
15 #include "lldb/Interpreter/CommandInterpreter.h"
16 #include "lldb/Interpreter/CommandObject.h"
17 #include "lldb/Interpreter/CommandReturnObject.h"
18 #include "lldb/Interpreter/OptionGroupFormat.h"
19 #include "lldb/Interpreter/OptionGroupValueObjectDisplay.h"
20 #include "lldb/Target/StackFrame.h"
21 #include "lldb/Utility/ConstString.h"
22 #include "lldb/lldb-defines.h"
23 #include "lldb/lldb-enumerations.h"
24 #include "lldb/lldb-forward.h"
25 #include "llvm/ADT/StringRef.h"
26
27 #include <regex>
28
29 using namespace llvm;
30 using namespace lldb;
31 using namespace lldb_private;
32
CommandObjectDWIMPrint(CommandInterpreter & interpreter)33 CommandObjectDWIMPrint::CommandObjectDWIMPrint(CommandInterpreter &interpreter)
34 : CommandObjectRaw(interpreter, "dwim-print",
35 "Print a variable or expression.",
36 "dwim-print [<variable-name> | <expression>]",
37 eCommandProcessMustBePaused | eCommandTryTargetAPILock) {
38
39 AddSimpleArgumentList(eArgTypeVarName);
40
41 m_option_group.Append(&m_format_options,
42 OptionGroupFormat::OPTION_GROUP_FORMAT |
43 OptionGroupFormat::OPTION_GROUP_GDB_FMT,
44 LLDB_OPT_SET_1);
45 StringRef exclude_expr_options[] = {"debug", "top-level"};
46 m_option_group.Append(&m_expr_options, exclude_expr_options);
47 m_option_group.Append(&m_varobj_options, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1);
48 m_option_group.Finalize();
49 }
50
GetOptions()51 Options *CommandObjectDWIMPrint::GetOptions() { return &m_option_group; }
52
DoExecute(StringRef command,CommandReturnObject & result)53 void CommandObjectDWIMPrint::DoExecute(StringRef command,
54 CommandReturnObject &result) {
55 m_option_group.NotifyOptionParsingStarting(&m_exe_ctx);
56 OptionsWithRaw args{command};
57 StringRef expr = args.GetRawPart();
58
59 if (expr.empty()) {
60 result.AppendErrorWithFormatv("'{0}' takes a variable or expression",
61 m_cmd_name);
62 return;
63 }
64
65 if (args.HasArgs()) {
66 if (!ParseOptionsAndNotify(args.GetArgs(), result, m_option_group,
67 m_exe_ctx))
68 return;
69 }
70
71 // If the user has not specified, default to disabling persistent results.
72 if (m_expr_options.suppress_persistent_result == eLazyBoolCalculate)
73 m_expr_options.suppress_persistent_result = eLazyBoolYes;
74 bool suppress_result = m_expr_options.ShouldSuppressResult(m_varobj_options);
75
76 auto verbosity = GetDebugger().GetDWIMPrintVerbosity();
77
78 Target *target_ptr = m_exe_ctx.GetTargetPtr();
79 // Fallback to the dummy target, which can allow for expression evaluation.
80 Target &target = target_ptr ? *target_ptr : GetDummyTarget();
81
82 EvaluateExpressionOptions eval_options =
83 m_expr_options.GetEvaluateExpressionOptions(target, m_varobj_options);
84 // This command manually removes the result variable, make sure expression
85 // evaluation doesn't do it first.
86 eval_options.SetSuppressPersistentResult(false);
87
88 DumpValueObjectOptions dump_options = m_varobj_options.GetAsDumpOptions(
89 m_expr_options.m_verbosity, m_format_options.GetFormat());
90 dump_options.SetHideRootName(suppress_result);
91
92 bool is_po = m_varobj_options.use_objc;
93
94 StackFrame *frame = m_exe_ctx.GetFramePtr();
95
96 // Either the language was explicitly specified, or we check the frame.
97 lldb::LanguageType language = m_expr_options.language;
98 if (language == lldb::eLanguageTypeUnknown && frame)
99 language = frame->GuessLanguage().AsLanguageType();
100
101 // Add a hint if object description was requested, but no description
102 // function was implemented.
103 auto maybe_add_hint = [&](llvm::StringRef output) {
104 // Identify the default output of object description for Swift and
105 // Objective-C
106 // "<Name: 0x...>. The regex is:
107 // - Start with "<".
108 // - Followed by 1 or more non-whitespace characters.
109 // - Followed by ": 0x".
110 // - Followed by 5 or more hex digits.
111 // - Followed by ">".
112 // - End with zero or more whitespace characters.
113 const std::regex swift_class_regex("^<\\S+: 0x[[:xdigit:]]{5,}>\\s*$");
114
115 if (GetDebugger().GetShowDontUsePoHint() && target_ptr &&
116 (language == lldb::eLanguageTypeSwift ||
117 language == lldb::eLanguageTypeObjC) &&
118 std::regex_match(output.data(), swift_class_regex)) {
119
120 static bool note_shown = false;
121 if (note_shown)
122 return;
123
124 result.GetOutputStream()
125 << "note: object description requested, but type doesn't implement "
126 "a custom object description. Consider using \"p\" instead of "
127 "\"po\" (this note will only be shown once per debug session).\n";
128 note_shown = true;
129 }
130 };
131
132 // Dump `valobj` according to whether `po` was requested or not.
133 auto dump_val_object = [&](ValueObject &valobj) {
134 if (is_po) {
135 StreamString temp_result_stream;
136 if (llvm::Error error = valobj.Dump(temp_result_stream, dump_options)) {
137 result.AppendError(toString(std::move(error)));
138 return;
139 }
140 llvm::StringRef output = temp_result_stream.GetString();
141 maybe_add_hint(output);
142 result.GetOutputStream() << output;
143 } else {
144 llvm::Error error =
145 valobj.Dump(result.GetOutputStream(), dump_options);
146 if (error) {
147 result.AppendError(toString(std::move(error)));
148 return;
149 }
150 }
151 result.SetStatus(eReturnStatusSuccessFinishResult);
152 };
153
154 // First, try `expr` as the name of a frame variable.
155 if (frame) {
156 auto valobj_sp = frame->FindVariable(ConstString(expr));
157 if (valobj_sp && valobj_sp->GetError().Success()) {
158 if (!suppress_result) {
159 if (auto persisted_valobj = valobj_sp->Persist())
160 valobj_sp = persisted_valobj;
161 }
162
163 if (verbosity == eDWIMPrintVerbosityFull) {
164 StringRef flags;
165 if (args.HasArgs())
166 flags = args.GetArgString();
167 result.AppendMessageWithFormatv("note: ran `frame variable {0}{1}`",
168 flags, expr);
169 }
170
171 dump_val_object(*valobj_sp);
172 return;
173 }
174 }
175
176 // Second, try `expr` as a persistent variable.
177 if (expr.starts_with("$"))
178 if (auto *state = target.GetPersistentExpressionStateForLanguage(language))
179 if (auto var_sp = state->GetVariable(expr))
180 if (auto valobj_sp = var_sp->GetValueObject()) {
181 dump_val_object(*valobj_sp);
182 return;
183 }
184
185 // Third, and lastly, try `expr` as a source expression to evaluate.
186 {
187 auto *exe_scope = m_exe_ctx.GetBestExecutionContextScope();
188 ValueObjectSP valobj_sp;
189 std::string fixed_expression;
190
191 ExpressionResults expr_result = target.EvaluateExpression(
192 expr, exe_scope, valobj_sp, eval_options, &fixed_expression);
193
194 // Only mention Fix-Its if the expression evaluator applied them.
195 // Compiler errors refer to the final expression after applying Fix-It(s).
196 if (!fixed_expression.empty() && target.GetEnableNotifyAboutFixIts()) {
197 Stream &error_stream = result.GetErrorStream();
198 error_stream << " Evaluated this expression after applying Fix-It(s):\n";
199 error_stream << " " << fixed_expression << "\n";
200 }
201
202 // If the expression failed, return an error.
203 if (expr_result != eExpressionCompleted) {
204 if (valobj_sp)
205 result.SetError(valobj_sp->GetError());
206 else
207 result.AppendErrorWithFormatv(
208 "unknown error evaluating expression `{0}`", expr);
209 return;
210 }
211
212 if (verbosity != eDWIMPrintVerbosityNone) {
213 StringRef flags;
214 if (args.HasArgs())
215 flags = args.GetArgStringWithDelimiter();
216 result.AppendMessageWithFormatv("note: ran `expression {0}{1}`", flags,
217 expr);
218 }
219
220 if (valobj_sp->GetError().GetError() != UserExpression::kNoResult)
221 dump_val_object(*valobj_sp);
222 else
223 result.SetStatus(eReturnStatusSuccessFinishResult);
224
225 if (suppress_result)
226 if (auto result_var_sp =
227 target.GetPersistentVariable(valobj_sp->GetName())) {
228 auto language = valobj_sp->GetPreferredDisplayLanguage();
229 if (auto *persistent_state =
230 target.GetPersistentExpressionStateForLanguage(language))
231 persistent_state->RemovePersistentVariable(result_var_sp);
232 }
233 }
234 }
235