/src/lib/regular_expression/internal/regular_expression_string_scanner.e
Specman e | 244 lines | 159 code | 25 blank | 60 comment | 3 complexity | ed6bfdfe7fd7f42fc36c745ed281e68d MD5 | raw file
1-- This file is part of a Liberty Eiffel library. 2-- See the full copyright at the end. 3-- 4class REGULAR_EXPRESSION_STRING_SCANNER 5 -- 6 -- Facility to scan strings 7 -- TODO improve it by using STRING_HANDLER and string's storage 8 -- 9 10feature {ANY} -- make 11 make 12 -- Initialise the attributes. 13 do 14 create last_string.make(10) 15 end 16 17feature {ANY} -- basic 18 scanned_string: ABSTRACT_STRING 19 -- The expression being currently build. 20 21 set_scanned_string (string: like scanned_string) 22 -- Set the 'scanned_string' with 'string'. 23 do 24 scanned_string := string 25 clear_error 26 goto_position(scanned_string.lower) 27 ensure 28 has_no_error: not has_error 29 definition: scanned_string = string 30 at_the_begin: position = scanned_string.lower 31 end 32 33feature {ANY} -- error management 34 has_error: BOOLEAN 35 -- True when an error was encountered 36 37 clear_error 38 -- Remove the error flag 39 do 40 has_error := False 41 ensure 42 has_no_error: not has_error 43 end 44 45 last_error: STRING 46 -- Returns a string recorded for the error. 47 require 48 has_error: has_error 49 do 50 Result := last_string 51 ensure 52 not_void: Result /= Void 53 end 54 55 set_error (message: STRING) 56 -- Set has_error and last_error. 57 -- The explaining error string 'last_error' 58 -- is created as follow: "Error at position 'position': 'message'.". 59 require 60 message_not_void: message /= Void 61 has_no_error: not has_error 62 do 63 has_error := True 64 last_string.clear_count 65 last_string.append_string(once "Error at position ") 66 position.append_in(last_string) 67 last_string.append_string(once ": ") 68 last_string.append_string(message) 69 last_string.append_character('.') 70 ensure 71 has_error: has_error 72 end 73 74feature {ANY} -- scanning 75 position: INTEGER 76 -- The scanned position. 77 -- It is the position of 'last_character'. 78 79 last_character: CHARACTER 80 -- The scanned character. 81 -- The last character read from 'scanned_string'. 82 83 valid_last_character: BOOLEAN 84 -- True when 'last_character' is valid. 85 -- Is like 'scanned_string.valid_index(position)' 86 87 valid_previous_character: BOOLEAN 88 -- True if the position-1 is a valid position. 89 require 90 scanned_string /= Void 91 do 92 Result := scanned_string.valid_index(position - 1) 93 ensure 94 definition: Result = scanned_string.valid_index(position - 1) 95 end 96 97 previous_character: like last_character 98 -- The character at position-1. 99 require 100 valid_previous_character 101 do 102 Result := scanned_string.item(position - 1) 103 ensure 104 definition: Result = scanned_string.item(position - 1) 105 end 106 107 valid_next_character: BOOLEAN 108 -- True if the position+1 is a valid position. 109 require 110 scanned_string /= Void 111 do 112 Result := scanned_string.valid_index(position + 1) 113 ensure 114 definition: Result = scanned_string.valid_index(position + 1) 115 end 116 117 next_character: like last_character 118 -- The character at position+1. 119 require 120 valid_next_character 121 do 122 Result := scanned_string.item(position + 1) 123 ensure 124 definition: Result = scanned_string.item(position + 1) 125 end 126 127 end_of_input: BOOLEAN 128 -- True when all the characters of 'scanned_string' 129 -- are scanned. 130 do 131 Result := not valid_last_character 132 ensure 133 implies_last_character_not_valid: Result implies not valid_last_character 134 end 135 136 goto_position (pos: INTEGER) 137 -- Change the currently scanned position to 'pos'. 138 -- Updates 'last_character' and 'valid_last_character' to 139 -- reflect the new position value. 140 require 141 has_no_error: not has_error 142 scanned_string /= Void 143 do 144 position := pos 145 valid_last_character := scanned_string.valid_index(pos) 146 if valid_last_character then 147 last_character := scanned_string.item(pos) 148 end 149 ensure 150 has_no_error: not has_error 151 position_set: position = pos 152 validity_updated: valid_last_character = scanned_string.valid_index(position) 153 character_updated: valid_last_character implies last_character = scanned_string.item(position) 154 end 155 156 read_character 157 -- Reads the next character. 158 require 159 has_no_error: not has_error 160 not_at_end: not end_of_input 161 do 162 goto_position(position + 1) 163 ensure 164 next_position: position > old position 165 has_no_error: not has_error 166 end 167 168 read_integer 169 -- Reads an integer value beginning at the 170 -- currently scanned position. 171 -- The read value is stored in 'last_integer'. 172 require 173 has_no_error: not has_error 174 not_at_end: not end_of_input 175 begin_with_a_digit: last_character.is_decimal_digit 176 do 177 from 178 last_integer := last_character.decimal_value 179 read_character 180 until 181 end_of_input or else not last_character.is_decimal_digit 182 loop 183 last_integer := 10 * last_integer + last_character.decimal_value 184 read_character 185 end 186 ensure 187 has_no_error: not has_error 188 digits_eaten: end_of_input or else not last_character.is_decimal_digit 189 end 190 191 saved_position: INTEGER 192 -- The saved position (only one is currently enough). 193 194 save_position 195 -- Saves the current scanning position. 196 require 197 not_at_end: not end_of_input 198 do 199 saved_position := position 200 ensure 201 not_at_end: not end_of_input 202 position_kept: position = old position 203 saved_position_set: saved_position = position 204 end 205 206 restore_saved_position 207 -- Restore the scanning position to the last saved one. 208 do 209 goto_position(saved_position) 210 ensure 211 position_restored: position = old saved_position 212 not_at_end: not end_of_input 213 end 214 215 last_string: STRING 216 -- A string buffer. 217 218 last_integer: INTEGER 219 -- An integer buffer. 220 221invariant 222 last_string_not_void: last_string /= Void 223 224end -- class REGULAR_EXPRESSION_STRING_SCANNER 225-- 226-- Copyright (C) 2009-2017: by all the people cited in the AUTHORS file. 227-- 228-- Permission is hereby granted, free of charge, to any person obtaining a copy 229-- of this software and associated documentation files (the "Software"), to deal 230-- in the Software without restriction, including without limitation the rights 231-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 232-- copies of the Software, and to permit persons to whom the Software is 233-- furnished to do so, subject to the following conditions: 234-- 235-- The above copyright notice and this permission notice shall be included in 236-- all copies or substantial portions of the Software. 237-- 238-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 239-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 240-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 241-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 242-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 243-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 244-- THE SOFTWARE.