Answer Happy

Modify the Mini-Triangle lexical grammar (Example 4.21) as follows. Allow identifiers to contain single embedded underscores, e.g.. set-up (but not 'set-up', nor 'set- . nor .-up'). Allow real-literals, with a decimal point surrounded by digits, e.g., "3.1416' (but not 4., nor *. 125'). Example 4.27 Scanner for Mini-Triangle The lexical grammar of Mini-Triangle is partly given by production rules (1.10) through (1.13). We add production rules for Token and Separator Token Identifier Integer-Literal Operator : : : - |-|(et Identifier Letter identifier Letter | Identifier Digit (4.15) Integer-Literal Digit Integer-Literal Digit (4.16) Operator + 1-1 111<1>1-11 (4.17) Separator Comment space col (4:18) Comment I Graphic col (4.19) In these production rules: space stands for a space character: col stands for an end-of-line *character': eot stands for an end-of-text 'character Visible characters can be expressed as themselves in (E)BNF, but these invisible characters cannot.) Also: Digit stands for one of the digits '0', '1'. .... or '9': Show the updated production rules and modify the Triangle Scanner source code accordingly