60 lines
2.5 KiB
Go
60 lines
2.5 KiB
Go
package starlark
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import (
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"go.starlark.net/syntax"
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)
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// This file defines an experimental API for the debugging tools.
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// Some of these declarations expose details of internal packages.
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// (The debugger makes liberal use of exported fields of unexported types.)
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// Breaking changes may occur without notice.
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// A Binding is the name and position of a binding identifier.
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type Binding struct {
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Name string
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Pos syntax.Position
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}
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// NumLocals returns the number of local variables of this frame.
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// It is zero unless fr.Callable() is a *Function.
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func (fr *frame) NumLocals() int { return len(fr.locals) }
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// Local returns the binding (name and binding position) and value of
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// the i'th local variable of the frame's function.
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// Beware: the value may be nil if it has not yet been assigned!
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//
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// The index i must be less than [NumLocals].
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// Local may be called only while the frame is active.
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//
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// This function is provided only for debugging tools.
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func (fr *frame) Local(i int) (Binding, Value) {
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return Binding(fr.callable.(*Function).funcode.Locals[i]), fr.locals[i]
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}
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// DebugFrame is the debugger API for a frame of the interpreter's call stack.
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//
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// Most applications have no need for this API; use CallFrame instead.
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//
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// It may be tempting to use this interface when implementing built-in
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// functions. Beware that reflection over the call stack is easily
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// abused, leading to built-in functions whose behavior is mysterious
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// and unpredictable.
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//
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// Clients must not retain a DebugFrame nor call any of its methods once
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// the current built-in call has returned or execution has resumed
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// after a breakpoint as this may have unpredictable effects, including
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// but not limited to retention of object that would otherwise be garbage.
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type DebugFrame interface {
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Callable() Callable // returns the frame's function
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NumLocals() int // returns the number of local variables in this frame
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Local(i int) (Binding, Value) // returns the binding and value of the (Starlark) frame's ith local variable
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Position() syntax.Position // returns the current position of execution in this frame
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}
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// DebugFrame returns the debugger interface for
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// the specified frame of the interpreter's call stack.
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// Frame numbering is as for Thread.CallFrame: 0 <= depth < thread.CallStackDepth().
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//
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// This function is intended for use in debugging tools.
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// Most applications should have no need for it; use CallFrame instead.
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func (thread *Thread) DebugFrame(depth int) DebugFrame { return thread.frameAt(depth) }
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