class Grizzled::String::Template::WindowsCmdStringTemplate
A string template that uses the Windows cmd.exe
syntax
+%varname%+ for variable references. A variable's name may consist of
alphanumerics and underscores. To include a literal “%” in a string, escape
it with a backslash (“%”).
Constants
- ESCAPED_PERCENT
- ESCAPED_PERCENT_PLACEHOLDER
Public Class Methods
Initialize a new WindowsCmdStringTemplate
. Supports various
hash options.
Parameters:
resolver
-
A hash-like object that can take a variable name (via the +[]+ function) and resolve its value, returning the value (which is converted to string) or
nil
. options
-
hash of options. See below.
Options:
:safe
-
true
for a safe template that substitutes a blank string for a non-existent variable, instead of throwing an exception. Defaults totrue
. :var_pattern
-
Regular expression pattern (as a string, not a Regexp object) to match a variable name. Defaults to “[A-Za-z0-9_]+”
# File lib/grizzled/string/template.rb, line 335 def initialize(resolver, options={}) super(resolver, options) var_pat = options.fetch(:var_pattern, "[A-Za-z0-9_]+") @var_re = %r{%(#{var_pat})%} end
Public Instance Methods
Parse the location of the first variable in the string. Subclasses should override this method.
Parameters:
s
-
the string
Returns a Variable
object, or nil
.
# File lib/grizzled/string/template.rb, line 398 def find_variable_ref(s) m = @var_re.match(s) if m.nil? nil else Variable.new(m.begin(0), m.end(0), m[1], nil) end end
# File lib/grizzled/string/template.rb, line 364 def handle_match(m, s) if (m[1].length % 2) == 1 # Odd number of backslashes before "%". Valid escape. b = m.begin(0) start = (b == 0 ? "" : s[0..(b-1)]) start + ESCAPED_PERCENT_PLACEHOLDER + pre_sub(s[m.end(0)..-1]) else # Even number of backslashes before "%". Not an escape. s end end
Kludge to handle escaped “%”. Temporarily replace it with something highly unlikely to be in the string. Then, put a single “%” in its place, after the substitution. Must be sure to handle even versus odd number of backslash characters.
# File lib/grizzled/string/template.rb, line 362 def pre_sub(s) def handle_match(m, s) if (m[1].length % 2) == 1 # Odd number of backslashes before "%". Valid escape. b = m.begin(0) start = (b == 0 ? "" : s[0..(b-1)]) start + ESCAPED_PERCENT_PLACEHOLDER + pre_sub(s[m.end(0)..-1]) else # Even number of backslashes before "%". Not an escape. s end end # Check for an escaped "%" m = ESCAPED_PERCENT.match(s) if (m) handle_match(m, s) else s end end
Replace all variable references in the given string. Variable references are recognized per the regular expression passed to the constructor. If a referenced variable is not found in the resolver, this method either:
-
throws a
VariableNotFoundException
(ifsafe
isfalse
). -
substitutes an empty string (if
safe
istrue
)
Recursive references are supported (but beware of infinite recursion).
Parameters:
s
-
the string in which to replace variable references
Returns the substituted result.
# File lib/grizzled/string/template.rb, line 356 def substitute(s) # Kludge to handle escaped "%". Temporarily replace it with # something highly unlikely to be in the string. Then, put a single # "%" in its place, after the substitution. Must be sure to handle # even versus odd number of backslash characters. def pre_sub(s) def handle_match(m, s) if (m[1].length % 2) == 1 # Odd number of backslashes before "%". Valid escape. b = m.begin(0) start = (b == 0 ? "" : s[0..(b-1)]) start + ESCAPED_PERCENT_PLACEHOLDER + pre_sub(s[m.end(0)..-1]) else # Even number of backslashes before "%". Not an escape. s end end # Check for an escaped "%" m = ESCAPED_PERCENT.match(s) if (m) handle_match(m, s) else s end end s2 = super(pre_sub(s)) s2.gsub(ESCAPED_PERCENT_PLACEHOLDER, '%') end