185d4964a1
Implements `dwim-print`, a printing command that chooses the most direct, efficient, and resilient means of printing a given expression. DWIM is an acronym for Do What I Mean. From Wikipedia, DWIM is described as: > attempt to anticipate what users intend to do, correcting trivial errors > automatically rather than blindly executing users' explicit but > potentially incorrect input The `dwim-print` command serves as a single print command for users who don't yet know, or prefer not to know, the various lldb commands that can be used to print, and when to use them. This initial implementation is the base foundation for `dwim-print`. It accepts no flags, only an expression. If the expression is the name of a variable in the frame, then effectively `frame variable` is used to get, and print, its value. Otherwise, printing falls back to using `expression` evaluation. In this initial version, frame variable paths will be handled with `expression`. Following this, there are a number of improvements that can be made. Some improvements include supporting `frame variable` expressions or registers. To provide transparency, especially as the `dwim-print` command evolves, a new setting is also introduced: `dwim-print-verbosity`. This setting instructs `dwim-print` to optionally print a message showing the effective command being run. For example `dwim-print var.meth()` can print a message such as: "note: ran `expression var.meth()`". See https://discourse.llvm.org/t/dwim-print-command/66078 for the proposal and discussion. Differential Revision: https://reviews.llvm.org/D138315
85 lines
2.9 KiB
C++
85 lines
2.9 KiB
C++
//===-- CommandObjectDWIMPrint.cpp ------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "CommandObjectDWIMPrint.h"
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#include "lldb/Core/ValueObject.h"
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#include "lldb/Interpreter/CommandInterpreter.h"
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#include "lldb/Interpreter/CommandObject.h"
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#include "lldb/Interpreter/CommandReturnObject.h"
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#include "lldb/Target/StackFrame.h"
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#include "lldb/Utility/ConstString.h"
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#include "lldb/lldb-enumerations.h"
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#include "lldb/lldb-forward.h"
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using namespace llvm;
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using namespace lldb;
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using namespace lldb_private;
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CommandObjectDWIMPrint::CommandObjectDWIMPrint(CommandInterpreter &interpreter)
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: CommandObjectRaw(
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interpreter, "dwim-print", "Print a variable or expression.",
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"dwim-print [<variable-name> | <expression>]",
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eCommandProcessMustBePaused | eCommandTryTargetAPILock |
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eCommandRequiresFrame | eCommandProcessMustBeLaunched |
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eCommandRequiresProcess) {}
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bool CommandObjectDWIMPrint::DoExecute(StringRef expr,
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CommandReturnObject &result) {
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// Ignore leading and trailing whitespace.
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expr = expr.trim();
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if (expr.empty()) {
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result.AppendErrorWithFormatv("'{0}' takes a variable or expression",
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m_cmd_name);
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return false;
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}
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// eCommandRequiresFrame guarantees a frame.
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StackFrame *frame = m_exe_ctx.GetFramePtr();
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assert(frame);
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auto verbosity = GetDebugger().GetDWIMPrintVerbosity();
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// First, try `expr` as the name of a variable.
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{
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auto valobj_sp = frame->FindVariable(ConstString(expr));
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if (valobj_sp && valobj_sp->GetError().Success()) {
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if (verbosity == eDWIMPrintVerbosityFull)
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result.AppendMessageWithFormatv("note: ran `frame variable {0}`", expr);
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valobj_sp->Dump(result.GetOutputStream());
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result.SetStatus(eReturnStatusSuccessFinishResult);
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return true;
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}
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}
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// Second, also lastly, try `expr` as a source expression to evaluate.
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{
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// eCommandRequiresProcess guarantees a target.
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Target *target = m_exe_ctx.GetTargetPtr();
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assert(target);
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ValueObjectSP valobj_sp;
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if (target->EvaluateExpression(expr, frame, valobj_sp) ==
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eExpressionCompleted) {
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if (verbosity != eDWIMPrintVerbosityNone)
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result.AppendMessageWithFormatv("note: ran `expression -- {0}`", expr);
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valobj_sp->Dump(result.GetOutputStream());
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result.SetStatus(eReturnStatusSuccessFinishResult);
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return true;
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} else {
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if (valobj_sp)
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result.SetError(valobj_sp->GetError());
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else
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result.AppendErrorWithFormatv(
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"unknown error evaluating expression `{0}`", expr);
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return false;
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}
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}
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}
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