How to Extract the String Value from a Go String Literal in an AST Node?

Retrieving String Value from Go String Literal Code

In a Go syntax tree manipulation scenario, you may need to extract the value of a string literal from an ast.BasicLit node. While this node indicates the string literal type, its value is represented as Go code instead of the actual string value. This article addresses the solution to this challenge.

Solution: strconv.Unquote()

The strconv.Unquote() function is the key to addressing this need. It enables the conversion of a string literal represented as Go code back to its unquoted value. However, it's crucial to note that strconv.Unquote() only unquotes strings enclosed in quotation marks ("). Thus, if the string literal in your ast.BasicLit node lacks quotation marks, you must manually add them before using strconv.Unquote().

Example Usage:

import (
    "fmt"
    "strconv"
)

func main() {
    // String literal without quotation marks (will fail)
    str1 := "Hello"

    // String literal with quotation marks (valid)
    str2 := `"Hello world"`

    // Manually adding quotation marks to the first string
    str1 = strconv.Quote(str1)

    // Unquoting the string literals
    unqStr1, _ := strconv.Unquote(str1)
    unqStr2, _ := strconv.Unquote(str2)

    fmt.Println(unqStr1) // Output: Hello
    fmt.Println(unqStr2) // Output: Hello world
}

Important Notes:

• strconv.Unquote() only unquotes strings within quotation marks.
• If the string literal contains special characters (e.g., line breaks), strconv.Quote() must be used before strconv.Unquote() for correct handling.
• The _ return values in the example are ignored for brevity; handle them appropriately in practical use cases.

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