1. A method of input control for text input boxes, comprising: at a device having one or more processors, memory, and a display: detecting selection of a text input box in a user interface; in response to detecting the selection of the text input box and prior to receiving input text for the text input box, obtaining a regular expression for acceptable input corresponding to text input box; for each character in the regular expression, determining whether the character belongs to a respective validation filter character set for a predetermined data type; in response to a determination that all characters in the regular expression belongs to the respective validation filter character set for the predetermined data type, selectively presenting a respective character keyboard corresponding to the predetermined data type to a user for text entry, wherein: the respective validation filter character set includes a subset of regular validation filter characters and a subset of special validation filter characters; and for each character in the regular expression, determining whether the character belongs to the respective validation filter character set for the predetermined data type further comprises: determining whether the character belongs to the subset of regular validation filter characters or the subset of special validation filter characters; in accordance with a determination that the character belongs to the subset of regular validation filter characters, proceeding to process a next character in the regular expression; and in accordance with a determination that the character belongs to the subset of special validation filter characters, processing all characters that fall between the character and a counterpart character of the character in the regular expression as a respective character subset; and in response to a determination that a current character in the regular expression does not belong to the respective validation filter character set for the predetermined data type, determining whether each character in the regular expression belongs to a respective validation filter character set for another predetermined data type.