Statically parse local -a A=(1 2) and declare -a A=(1 2).

Note that we accept flags but don't do anything with them yet.  The
variable is known to be an array from the RHS, not LHS.

We might have to parse these dynamically later, as with 'export', but so
far all usages are static.

Addresses issue #26.

core/cmd_exec.py

@@ -649,6 +649,12 @@ def _Dispatch(self, node, fork_external):
      if node.keyword == Id.Assign_Local:
        lookup_mode = scope.LocalOnly
        flags = ()
      elif node.keyword == Id.Assign_Declare:
        # declare is like local, except it can also be used outside functions?
        lookup_mode = scope.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.Dynamic
        flags = (var_flags.ReadOnly,)

osh/cmd_parse.py

@@ -439,13 +439,28 @@ def _MakeSimpleCommand(self, prefix_bindings, suffix_words, redirects):
    return node

  def _MakeAssignment(self, assign_kw, suffix_words):
    flags = []
    bindings = []
    for i, w in enumerate(suffix_words):
      if i == 0:
        continue  # skip over local, export, etc.

      left_spid = word.LeftMostSpanForWord(w)
    # First parse flags, e.g. -r -x -a -A.  None of the flags have arguments.
    n = len(suffix_words)
    i = 1
    while i < n:
      w = suffix_words[i]
      ok, static_val, quoted = word.StaticEval(w)
      if not ok or quoted:
        break  # can't statically evaluate

      if static_val.startswith('-'):
        flags.append(static_val)
      else:
        break  # not a flag, rest are args
      i += 1

    # Now parse bindings or variable names
    while i < n:
      w = suffix_words[i]
      left_spid = word.LeftMostSpanForWord(w)
      kv = word.LooksLikeAssignment(w)
      if kv:
        k, v = kv
@@ -462,19 +477,20 @@ def _MakeAssignment(self, assign_kw, suffix_words):
        # Parse this differently then?
        # dynamic-export?
        # It sets global variables.

        ok, value, quoted = word.StaticEval(w)
        ok, static_val, quoted = word.StaticEval(w)
        if not ok or quoted:
          self.AddErrorContext(
              'Variable names must be constant strings, got %s', w, word=w)
          return None
        pair = (value, None, left_spid)  # No value is equivalent to ''
        m = VAR_NAME_RE.match(value)
           self.AddErrorContext(
               'Variable names must be constant strings, got %s', w, word=w)
           return None

        pair = (static_val, None, left_spid)  # No value is equivalent to ''
        m = VAR_NAME_RE.match(static_val)
        if not m:
          self.AddErrorContext('Invalid variable name %r', value, word=w)
          self.AddErrorContext('Invalid variable name %r', static_val, word=w)
          return None

      bindings.append(pair)
      i += 1

    # TODO: Also make with LhsIndexedName
    pairs = []
@@ -483,7 +499,7 @@ def _MakeAssignment(self, assign_kw, suffix_words):
      p.spids.append(spid)
      pairs.append(p)

    node = ast.Assignment(assign_kw, pairs)
    node = ast.Assignment(assign_kw, flags, pairs)

    return node

osh/osh.asdl

@@ -158,8 +158,7 @@ module osh
    -- TODO: respect order 
  | SimpleCommand(word* words, redir* redirects, env_pair* more_env)
  | Sentence(command child, token terminator)
    -- TODO: parse flags -r -x; -a and -A aren't needed
  | Assignment(id keyword, assign_pair* pairs)
  | Assignment(id keyword, string* flags, assign_pair* pairs)
  | ControlFlow(token token, word? arg_word)
  | Pipeline(command* children, bool negated, int* stderr_indices)
    -- TODO: Should be left and right

spec/assign.test.sh

@@ -68,3 +68,26 @@ echo "v=$v"
# OK bash/dash/mksh stdout: v=None
# OK bash/dash/mksh status: 0
# status: 2

### local -a
# nixpkgs setup.sh uses this (issue #26)
f() {
  local -a array=(x y z)
  argv "${array[@]}"
}
f
# stdout: ['x', 'y', 'z']
# N-I dash stdout-json: ""
# N-I dash status: 2
# N-I mksh stdout-json: ""
# N-I mksh status: 1

### declare -a
# nixpkgs setup.sh uses this (issue #26)
declare -a array=(x y z)
argv "${array[@]}"
# stdout: ['x', 'y', 'z']
# N-I dash stdout-json: ""
# N-I dash status: 2
# N-I mksh stdout-json: ""
# N-I mksh status: 1