"let number = 100" を Syntax でマッチ

main.swift

import Foundation
import SwiftSyntax
import SwiftParser

let sourceFile = Parser.parse(source: "let number = 100")
print(sourceFile.debugDescription)

func getLetMethod() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        print(decl.bindingSpecifier.text) // let
    }
}

func getNumberMethod() {
    let statements = Array(sourceFile.statements)
    let codeBlock = statements[0]
    let item = codeBlock.item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let pattern = binding.pattern.as(IdentifierPatternSyntax.self) {
            let identifier = pattern.identifier
            print(identifier) // number
        }

    }
}

func getEqual() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let initializer = binding.initializer?.as(InitializerClauseSyntax.self) {
            print(initializer.equal.text) // =
        }
    }
}

func get100Method() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let initializer = binding.initializer?.as(InitializerClauseSyntax.self) {
            if let value = initializer.value.as(IntegerLiteralExprSyntax.self) {
                print(value.literal) // 100
            }

        }
    }
}

置き換え.swift

import Foundation
import SwiftSyntax
import SwiftParser

let sourceFile = Parser.parse(source: "let number = 100")
print(sourceFile.debugDescription)

func getLetMethod() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        print(decl.bindingSpecifier) // let
        let result = decl.with(\.bindingSpecifier, .keyword(SwiftSyntax.Keyword.var))
        print(result.bindingSpecifier) // var
    }
}

func getNumberMethod() {
    let statements = Array(sourceFile.statements)
    let codeBlock = statements[0]
    let item = codeBlock.item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let pattern = binding.pattern.as(IdentifierPatternSyntax.self) {
            let identifier = pattern.identifier
            print(identifier) // number
            let result = pattern.with(\.identifier, .identifier("amount"))
            print(result.description) // amount
        }

    }
}

func getEqual() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let initializer = binding.initializer?.as(InitializerClauseSyntax.self) {
            print(initializer.equal) // =
        }
    }
}

func get100Method() {
    let statements = Array(sourceFile.statements)
    let item = statements[0].item
    if let decl = item.as(VariableDeclSyntax.self) {
        let bindings = Array(decl.bindings)
        let binding = bindings[0]
        if let initializer = binding.initializer?.as(InitializerClauseSyntax.self) {
            if let value = initializer.value.as(IntegerLiteralExprSyntax.self) {
                print(value.literal) // 100
                let result = value.with(\.literal, .floatLiteral("100.0"))
                print(result.literal) // 100.0
            }

        }
    }
}