Respect flags like -r and -x to assignment keywords.

declare/typeset, local, and readonly all take the same flags.

NOTE: We still don't do anything with -a.  'local -a foo' in bash
creates a cell for a variable that is STILL undefined.  That is,
evaluating it will fail in 'set -o nounset' mode.

Addresses issue #59.

core/cmd_exec.py

@@ -39,6 +39,7 @@
from core import process
from core import runtime
from core import state
from core import word_compile

from osh import ast_ as ast
from osh import parse_lib
@@ -738,25 +739,23 @@ def _Dispatch(self, node, fork_external):

    elif node.tag == command_e.Assignment:
      pairs = []
      flags = word_compile.ParseAssignFlags(node.flags)

      if node.keyword == Id.Assign_Local:
        lookup_mode = scope_e.LocalOnly
        flags = ()
      # typeset and declare are synonyms?  I see typeset -a a=() the most.
      elif node.keyword in (Id.Assign_Declare, Id.Assign_Typeset):
        # declare is like local, except it can also be used outside functions?
        lookup_mode = scope_e.LocalOnly
        # TODO: Respect flags.  -r and -x matter, but -a and -A might be
        # implicit in the RHS?
        flags = ()
      elif node.keyword == Id.Assign_Readonly:
        lookup_mode = scope_e.Dynamic
        flags = (var_flags_e.ReadOnly,)
        flags.append(var_flags_e.ReadOnly)
      elif node.keyword == Id.Assign_None:  # mutate existing local or global
        lookup_mode = scope_e.Dynamic
        flags = ()
      else:
        # TODO: typeset, declare, etc.  Those are dynamic though.
        raise NotImplementedError(node.keyword)
        raise AssertionError(node.keyword)

      for pair in node.pairs:
        if pair.op == assign_op_e.PlusEqual:
@@ -790,6 +789,9 @@ def _Dispatch(self, node, fork_external):
            # e.g. 'readonly x' or 'local x'
            val = None  # only changing flags

        # NOTE: In bash and mksh, declare -a myarray makes an empty cell with
        # Undef value, but the 'array' attribute.

        self.mem.SetVar(lval, val, flags, lookup_mode)

        # Assignment always appears to have a spid.

core/word_compile.py

@@ -7,6 +7,10 @@
"""

from core.id_kind import Id
from core import runtime

var_flags_e = runtime.var_flags_e


_ONE_CHAR = {
    '0': '\0',
@@ -75,3 +79,31 @@ def EvalCStringToken(id_, value):
  else:
    raise AssertionError


#
# Assignment
#

def ParseAssignFlags(flag_args):
  """
  Args:
    flag_args looks like ['-r', '-x'] or ['-rx'], etc.

  Returns:
    A list of var_flags_e

  NOTE: Any errors should be caught at PARSE TIME, not compile time.
  """
  flags = []
  for arg in flag_args:
    assert arg[0] == '-', arg
    for char in arg[1:]:
      if char == 'x':
        flags.append(var_flags_e.Exported)
      elif char == 'r':
        flags.append(var_flags_e.ReadOnly)
      else:
        # -a is ignored right now?
        pass
  return flags

spec/array.test.sh

@@ -369,3 +369,24 @@ echo ${#a[@]} ${#b[@]} ${#c[@]} ${#d[@]}
4 4 4 4
1 1 1 1
## END

### declare -a / local -a is empty array
declare -a myarray
argv.py "${myarray[@]}"
myarray+=('x')
argv.py "${myarray[@]}"

f() {
  local -a myarray
  argv.py "${myarray[@]}"
  myarray+=('x')
  argv.py "${myarray[@]}"
}
f
## STDOUT:
[]
['x']
[]
['x']
## END

spec/assign.test.sh

@@ -290,3 +290,88 @@ echo $?
127
127
## END

### typeset -r makes a string readonly
typeset -r s1='12'
typeset -r s2='34'

s1='c'
echo status=$?
s2='d'
echo status=$?

s1+='e'
echo status=$?
s2+='f'
echo status=$?

unset s1
echo status=$?
unset s2
echo status=$?

## status: 1
## stdout-json: ""
## OK mksh status: 2
## OK bash status: 0
## OK bash STDOUT:
status=1
status=1
status=1
status=1
status=1
status=1
## END
## OK dash status: 0
## N-I dash STDOUT:
status=0
status=0
status=127
status=127
status=0
status=0
## END

### typeset -ar makes it readonly
typeset -a -r array1=(1 2)
typeset -ar array2=(3 4)

array1=('c')
echo status=$?
array2=('d')
echo status=$?

array1+=('e')
echo status=$?
array2+=('f')
echo status=$?

unset array1
echo status=$?
unset array2
echo status=$?

## status: 1
## stdout-json: ""
## OK bash status: 0
## OK bash STDOUT:
status=1
status=1
status=1
status=1
status=1
status=1
## END
# N-I dash status: 2
# N-I dash stdout-json: ""
# N-I mksh status: 1
# N-I mksh stdout-json: ""

### typeset -x makes it exported
typeset -rx PYTHONPATH=lib/
printenv.py PYTHONPATH
## STDOUT:
lib/
## END
# N-I dash stdout: None