1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
module JGrep
class Parser
attr_reader :scanner, :execution_stack
def initialize(args)
@scanner = Scanner.new(args)
@execution_stack = []
parse
end
# Parse the input string, one token at a time a contruct the call stack
def parse(substatement = nil, token_index = 0)
p_token = nil
if substatement
c_token, c_token_value = substatement[token_index]
else
c_token, c_token_value = @scanner.get_token
end
parenth = 0
until c_token.nil?
if substatement
token_index += 1
n_token, n_token_value = substatement[token_index]
else
@scanner.token_index += 1
n_token, n_token_value = @scanner.get_token
end
next if n_token == " "
case c_token
when "and"
unless (n_token =~ /not|statement|\(|\+|-/) || (scanner.token_index == scanner.arguments.size)
raise "Error at column #{scanner.token_index}. \nExpected 'not', 'statement' or '('. Found '#{n_token_value}'"
end
raise "Error at column #{scanner.token_index}. \n Expression cannot start with 'and'" if p_token.nil?
raise "Error at column #{scanner.token_index}. \n #{p_token} cannot be followed by 'and'" if %w[and or].include?(p_token)
when "or"
unless (n_token =~ /not|statement|\(|\+|-/) || (scanner.token_index == scanner.arguments.size)
raise "Error at column #{scanner.token_index}. \nExpected 'not', 'statement', '('. Found '#{n_token_value}'"
end
raise "Error at column #{scanner.token_index}. \n Expression cannot start with 'or'" if p_token.nil?
raise "Error at column #{scanner.token_index}. \n #{p_token} cannot be followed by 'or'" if %w[and or].include?(p_token)
when "not"
unless n_token =~ /statement|\(|not|\+|-/
raise "Error at column #{scanner.token_index}. \nExpected 'statement' or '('. Found '#{n_token_value}'"
end
when "statement"
if c_token_value.is_a? Array
raise "Error at column #{scanner.token_index}\nError, cannot define '[' in a '[...]' block." if substatement
parse(c_token_value, 0)
end
if c_token_value.is_a?(String) && c_token_value =~ /!=/
c_token_value = c_token_value.gsub("!=", "=")
@execution_stack << {"not" => "not"}
end
if !n_token.nil? && !n_token.match(/and|or|\)/)
raise "Error at column #{scanner.token_index}. \nExpected 'and', 'or', ')'. Found '#{n_token_value}'"
end
when "+"
if !n_token.nil? && !n_token.match(/and|or|\)/)
raise "Error at column #{scanner.token_index}. \nExpected 'and', 'or', ')'. Found '#{n_token_value}'"
end
when "-"
if !n_token.nil? && !n_token.match(/and|or|\)/)
raise "Error at column #{scanner.token_index}. \nExpected 'and', 'or', ')'. Found '#{n_token_value}'"
end
when ")"
if !n_token.nil? && n_token !~ /|and|or|not|\(/
raise "Error at column #{scanner.token_index}. \nExpected 'and', 'or', 'not' or '('. Found '#{n_token_value}'"
end
parenth += 1
when "("
unless n_token =~ /statement|not|\(|\+|-/
raise "Error at column #{scanner.token_index}. \nExpected 'statement', '(', not. Found '#{n_token_value}'"
end
parenth -= 1
else
raise "Unexpected token found at column #{scanner.token_index}. '#{c_token_value}'"
end
unless n_token == " " || substatement
@execution_stack << {c_token => c_token_value}
end
p_token = c_token
c_token = n_token
c_token_value = n_token_value
end
return if substatement
raise "Error. Missing parentheses ')'." if parenth < 0
raise "Error. Missing parentheses '('." if parenth > 0
end
end
end
|
