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janet/examples/debugger.janet
2019-12-17 23:06:41 -06:00

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###
### A useful debugger library for Janet. Should be used
### inside a debug repl.
###
(defn .fiber
"Get the current fiber being debugged."
[]
(if-let [entry (dyn '_fiber)]
(entry :value)
(dyn :fiber)))
(defn .stack
"Print the current fiber stack"
[]
(print)
(debug/stacktrace (.fiber) "")
(print))
(defn .frame
"Show a stack frame"
[&opt n]
(def stack (debug/stack (.fiber)))
(in stack (or n 0)))
(defn .fn
"Get the current function"
[&opt n]
(in (.frame n) :function))
(defn .slots
"Get an array of slots in a stack frame"
[&opt n]
(in (.frame n) :slots))
(defn .slot
"Get the value of the nth slot."
[&opt nth frame-idx]
(in (.slots frame-idx) (or nth 0)))
(defn .quit
"Resume (dyn :fiber) with the value passed to it after exiting the debugger."
[&opt val]
(setdyn :exit true)
(setdyn :resume-value val)
nil)
(defn .disasm
"Gets the assembly for the current function."
[&opt n]
(def frame (.frame n))
(def func (frame :function))
(disasm func))
(defn .bytecode
"Get the bytecode for the current function."
[&opt n]
((.disasm n) 'bytecode))
(defn .ppasm
"Pretty prints the assembly for the current function"
[&opt n]
(def frame (.frame n))
(def func (frame :function))
(def dasm (disasm func))
(def bytecode (dasm 'bytecode))
(def pc (frame :pc))
(def sourcemap (dasm 'sourcemap))
(var last-loc [-2 -2])
(print "\n function: " (dasm 'name) " [" (in dasm 'source "") "]")
(when-let [constants (dasm 'constants)]
(printf " constants: %.4Q" constants))
(printf " slots: %.4Q\n" (frame :slots))
(def padding (string/repeat " " 20))
(loop [i :range [0 (length bytecode)]
:let [instr (bytecode i)]]
(prin (if (= (tuple/type instr) :brackets) "*" " "))
(prin (if (= i pc) "> " " "))
(prinf "\e[33m%.20s\e[0m" (string (string/join (map string instr) " ") padding))
(when sourcemap
(let [[sl sc] (sourcemap i)
loc [sl sc]]
(when (not= loc last-loc)
(set last-loc loc)
(prin " # line " sl ", column " sc))))
(print))
(print))
(defn .source
"Show the source code for the function being debugged."
[&opt n]
(def frame (.frame n))
(def s (frame :source))
(def all-source (slurp s))
(print "\n\e[33m" all-source "\e[0m\n"))
(defn .breakall
"Set breakpoints on all instructions in the current function."
[&opt n]
(def fun (.fn n))
(def bytecode (.bytecode n))
(for i 0 (length bytecode)
(debug/fbreak fun i))
(print "Set " (length bytecode) " breakpoints in " fun))
(defn .clearall
"Clear all breakpoints on the current function."
[&opt n]
(def fun (.fn n))
(def bytecode (.bytecode n))
(for i 0 (length bytecode)
(debug/unfbreak fun i))
(print "Cleared " (length bytecode) " breakpoints in " fun))
(defn .break
"Set breakpoint at the current pc."
[]
(def frame (.frame))
(def fun (frame :function))
(def pc (frame :pc))
(debug/fbreak fun pc)
(print "Set breakpoint in " fun " at pc=" pc))
(defn .clear
"Clear the current breakpoint"
[]
(def frame (.frame))
(def fun (frame :function))
(def pc (frame :pc))
(debug/unfbreak fun pc)
(print "Cleared breakpoint in " fun " at pc=" pc))
(defn .next
"Go to the next breakpoint."
[&opt n]
(var res nil)
(for i 0 (or n 1)
(set res (resume (.fiber))))
res)
(defn .nextc
"Go to the next breakpoint, clearing the current breakpoint."
[&opt n]
(.clear)
(.next n))
(defn .step
"Execute the next n instructions."
[&opt n]
(var res nil)
(for i 0 (or n 1)
(set res (debug/step (.fiber))))
res)