From 8aed791e15eb650b9832c6808c3261dd562ac9af Mon Sep 17 00:00:00 2001
From: Charles Cooper <cooper.charles.m@gmail.com>
Date: Thu, 9 May 2019 12:01:59 -0700
Subject: [PATCH] Add a 'step' command to vdb

---
 bin/vyper-run            |  3 +++
 vdb/debug_computation.py | 26 +++++++++++++++++---------
 vdb/vdb.py               | 10 +++++++++-
 3 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/bin/vyper-run b/bin/vyper-run
index 3e30f38..c2408ee 100755
--- a/bin/vyper-run
+++ b/bin/vyper-run
@@ -30,6 +30,7 @@ if tb_limit:
 aparser = argparse.ArgumentParser(description='Vyper {0} quick CLI runner'.format(vyper.__version__))
 aparser.add_argument('input_file', help='Vyper sourcecode to run')
 aparser.add_argument('call_list', help='call list, without parameters: func, with parameters func(1, 2, 3). Semicolon separated')
+aparser.add_argument('--trace', action='store_true', help='very verbose logging')
 aparser.add_argument('-i', help='init args, comma separated', default=None, dest='init_args')
 
 args = aparser.parse_args()
@@ -133,6 +134,8 @@ if __name__ == '__main__':
         init_args = args.init_args.split(',') if args.init_args else []
         tester, w3 = get_tester(code)
 
+        setattr(vdb.debug_computation.DebugComputation, 'trace', args.trace)
+
         # Built list of calls to make.
         calls = []
         for signature in args.call_list.split(';'):
diff --git a/vdb/debug_computation.py b/vdb/debug_computation.py
index 2a73840..4b27d53 100644
--- a/vdb/debug_computation.py
+++ b/vdb/debug_computation.py
@@ -27,17 +27,22 @@ class DebugComputation(ByzantiumComputation):
     source_map = None
     stdin = None
     stdout = None
+    step_mode = False
+    trace = False
+    pc = 0
 
     @classmethod
     def run_debugger(self, computation, line_no):
-        VyperDebugCmd(
+        res = VyperDebugCmd(
             computation,
             line_no=line_no,
             source_code=self.source_code,
             source_map=self.source_map,
             stdin=self.stdin,
             stdout=self.stdout
-        ).cmdloop()
+        )
+        res.cmdloop()
+        self.step_mode = res.step_mode
         return line_no
 
     @classmethod
@@ -82,16 +87,19 @@ class DebugComputation(ByzantiumComputation):
                 opcode_fn = computation.get_opcode_fn(opcode)
 
                 pc_to_execute = max(0, computation.code.pc - 1)
-                computation.logger.trace(
-                    "OPCODE: 0x%x (%s) | pc: %s",
-                    opcode,
-                    opcode_fn.mnemonic,
-                    pc_to_execute,
-                )
+                if cls.trace:
+                    print(
+                        "NEXT OPCODE: 0x%x (%s) | pc: %s..%s" %
+                        (opcode,
+                        opcode_fn.mnemonic,
+                        cls.pc,
+                        pc_to_execute)
+                    )
+                cls.pc = pc_to_execute
 
                 is_breakpoint, line_no = cls.is_breakpoint(pc_to_execute, continue_line_nos)
 
-                if is_breakpoint and cls.enable_debug:
+                if (is_breakpoint or cls.step_mode) and cls.enable_debug:
                     cls.run_debugger(computation, line_no)
                     continue_line_nos.append(line_no)
 
diff --git a/vdb/vdb.py b/vdb/vdb.py
index 34bc24d..8de7d28 100644
--- a/vdb/vdb.py
+++ b/vdb/vdb.py
@@ -49,6 +49,7 @@ class VyperDebugCmd(cmd.Cmd):
         self.line_no = line_no
         self.global_vars = source_map.get("globals", {})
         self.local_vars = source_map.get("locals", {})
+        self.step_mode = False
         super().__init__(stdin=stdin, stdout=stdout)
         if stdout or stdin:
             self.use_rawinput = False
@@ -74,9 +75,15 @@ class VyperDebugCmd(cmd.Cmd):
         self._print_code_position()
 
     def postloop(self):
-        self.stdout.write('Exiting vdb' + '\n')
+        if not self.step_mode:
+            self.stdout.write('Exiting vdb' + '\n')
         super().postloop()
 
+    def do_step(self, *args):
+        """ Step to next instruction """
+        self.step_mode = True
+        return True
+
     def do_state(self, *args):
         """ Show current EVM state information. """
         self.stdout.write('Block Number => {}'.format(self.computation.state.block_number) + '\n')
@@ -208,6 +215,7 @@ class VyperDebugCmd(cmd.Cmd):
 
     def do_continue(self, *args):
         """ Exit vdb """
+        self.step_mode = False
         return True
 
     def do_EOF(self, line):