diff options
Diffstat (limited to 'eval.go')
| -rw-r--r-- | eval.go | 38 |
1 files changed, 24 insertions, 14 deletions
@@ -62,11 +62,12 @@ func (thread *Thread) Local(key string) interface{} { return thread.locals[key] } -// Caller returns the frame of the innermost enclosing Skylark function. +// Caller returns the frame of the caller of the current function. // It should only be used in built-ins called from Skylark code. -func (thread *Thread) Caller() *Frame { - return thread.frame -} +func (thread *Thread) Caller() *Frame { return thread.frame.parent } + +// TopFrame returns the topmost stack frame. +func (thread *Thread) TopFrame() *Frame { return thread.frame } // A StringDict is a mapping from names to values, and represents // an environment such as the global variables of a module. @@ -104,15 +105,19 @@ func (d StringDict) Freeze() { // Has reports whether the dictionary contains the specified key. func (d StringDict) Has(key string) bool { _, ok := d[key]; return ok } -// A Frame holds the execution state of a single Skylark function call -// or module toplevel. +// A Frame records a call to a Skylark function (including module toplevel) +// or a built-in function or method. type Frame struct { - parent *Frame // caller's frame (or nil) - posn syntax.Position // source position of PC, set during error - callpc uint32 // PC of position of active call, set during call - fn *Function // current function (or toplevel) + parent *Frame // caller's frame (or nil) + callable Callable // current function (or toplevel) or built-in + posn syntax.Position // source position of PC, set during error + callpc uint32 // PC of position of active call, set during call } +// The Frames of a thread are structured as a spaghetti stack, not a +// slice, so that an EvalError can copy a stack efficiently and immutably. +// In hindsight using a slice would have led to a more convenient API. + func (fr *Frame) errorf(posn syntax.Position, format string, args ...interface{}) *EvalError { fr.posn = posn msg := fmt.Sprintf(format, args...) @@ -124,11 +129,16 @@ func (fr *Frame) Position() syntax.Position { if fr.posn.IsValid() { return fr.posn // leaf frame only (the error) } - return fr.fn.funcode.Position(fr.callpc) // position of active call + if fn, ok := fr.callable.(*Function); ok { + return fn.funcode.Position(fr.callpc) // position of active call + } + return syntax.MakePosition(&builtinFilename, 1, 0) } -// Function returns the frame's function, or nil for the top-level of a module. -func (fr *Frame) Function() *Function { return fr.fn } +var builtinFilename = "<builtin>" + +// Function returns the frame's function or built-in. +func (fr *Frame) Callable() Callable { return fr.callable } // Parent returns the frame of the enclosing function call, if any. func (fr *Frame) Parent() *Frame { return fr.parent } @@ -157,7 +167,7 @@ func (fr *Frame) WriteBacktrace(out *bytes.Buffer) { print = func(fr *Frame) { if fr != nil { print(fr.parent) - fmt.Fprintf(out, " %s: in %s\n", fr.Position(), fr.fn.Name()) + fmt.Fprintf(out, " %s: in %s\n", fr.Position(), fr.Callable().Name()) } } print(fr) |