def EvalPrompt(self, val):
"""Perform the two evaluations that bash does. Used by $PS1 and ${x@P}."""
if val.tag != value_e.Str:
return self.default_prompt # no evaluation necessary
# Parse backslash escapes (cached)
try:
tokens = self.tokens_cache[val.s]
except KeyError:
tokens = list(match.PS1_LEXER.Tokens(val.s))
self.tokens_cache[val.s] = tokens
# Replace values.
ps1_str = self._ReplaceBackslashCodes(tokens)
# Parse it like a double-quoted word (cached). TODO: This could be done on
# mem.SetVar(), so we get the error earlier.
# NOTE: This is copied from the PS4 logic in Tracer.
try:
ps1_word = self.parse_cache[ps1_str]
except KeyError:
w_parser = self.parse_ctx.MakeWordParserForPlugin(ps1_str)
try:
ps1_word = w_parser.ReadForPlugin()
except util.ParseError as e:
ps1_word = word.ErrorWord("<ERROR: Can't parse PS1: %s>", e)
self.parse_cache[ps1_str] = ps1_word
# Evaluate, e.g. "${debian_chroot}\u" -> '\u'
val2 = self.ex.word_ev.EvalForPlugin(ps1_word)
return val2.s
def _EvalPS4(self):
"""For set -x."""
val = self.mem.GetVar('PS4')
assert val.tag == value_e.Str
s = val.s
if s:
first_char, ps4 = s[0], s[1:]
else:
first_char, ps4 = '+', ' ' # default
# NOTE: This cache is slightly broken because aliases are mutable! I think
# that is more or less harmless though.
try:
ps4_word = self.parse_cache[ps4]
except KeyError:
# We have to parse this at runtime. PS4 should usually remain constant.
w_parser = self.parse_ctx.MakeWordParserForPlugin(ps4)
try:
ps4_word = w_parser.ReadForPlugin()
except util.ParseError as e:
ps4_word = word.ErrorWord("<ERROR: Can't parse PS4: %s>", e)
self.parse_cache[ps4] = ps4_word
#print(ps4_word)
# TODO: Repeat first character according process stack depth. Where is
# that stored? In the executor itself? It should be stored along with
# the PID. Need some kind of ShellProcessState or something.
#
# We should come up with a better mechanism. Something like $PROC_INDENT
# and $OIL_XTRACE_PREFIX.
# Prevent infinite loop when PS4 has command sub!
assert self.exec_opts.xtrace # We shouldn't call this unless it's on!
self.exec_opts.xtrace = False
try:
prefix = self.word_ev.EvalForPlugin(ps4_word)
finally:
self.exec_opts.xtrace = True
return first_char, prefix.s