go - 如何检测语句结束？

Question

我不会 Go，我只是在研究各种语言的语法。

来自 Go FAQ:“Go 借用了 BCPL 的一个技巧:分隔语句的分号在正式语法中，但在可能是语句结尾的任何行的末尾由词法分析器自动注入(inject)，没有前瞻性”

我想知道它是如何完成的，我查看了 lex.go 但也许我对 Go 的了解不够(实际上很少)但我没有找到任何对“语句”的引用"或 "分号"。

那么，您如何在词法分析器阶段检测到有效语句的结尾而无需先行查看？

Answer 1

你可以看看语言规范:

The formal grammar uses semicolons ";" as terminators in a number of productions. Go programs may omit most of these semicolons using the following two rules:

When the input is broken into tokens, a semicolon is automatically inserted into the token stream at the end of a non-blank line if the line's final token is

• an identifier
• an integer, floating-point, imaginary, rune, or string literal
• one of the keywords break, continue, fallthrough, or return
• one of the operators and delimiters ++, --, ), ], or }

To allow complex statements to occupy a single line, a semicolon may be omitted before a closing ")" or "}".

http://golang.org/ref/spec#Semicolons