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  1. fn main() {
  2.     let source = "
  3.     var A as Integer
  4.     print A
  5.     A = 10
  6.     print A
  7.     A += 5
  8.     print A
  9.     A += -3
  10.     print A
  11.     ";
  12.  
  13.     let code_block = parse(source);
  14.  
  15.     run(code_block);
  16. }
  17.  
  18. fn parse(source: Str) -> CodeBlock {
  19.     let mut code_block = CodeBlock::new();
  20.  
  21.     for line in source.lines() {
  22.         let tokens: Vec<_> = line.split_whitespace().collect();
  23.         match tokens.first() {
  24.             Some(&"var") => code_block.push(Code::Var(tokens[1], tokens[3])),
  25.             Some(&"print") => code_block.push(Code::Print(tokens[1])),
  26.             Some(v) => {
  27.                 if tokens[1] == "=" {
  28.                     code_block.push(Code::Copy(v, tokens[2]))
  29.                 } else {
  30.                     code_block.push(Code::AddInto(v, tokens[2]))
  31.                 }
  32.             }
  33.             _ => {}
  34.         }
  35.     }
  36.     code_block
  37. }
  38.  
  39. fn run(code_block: CodeBlock) {
  40.     let mut integer_vars = std::collections::HashMap::new();
  41.     for code in &code_block {
  42.         match code {
  43.             Code::Var(var_name, var_type) => {
  44.                 if *var_type == "Integer" {
  45.                     integer_vars.insert(var_name, 0i32);
  46.                 }
  47.             }
  48.             Code::Copy(var_name, new_value) => {
  49.                 if let Some(var_value) = integer_vars.get_mut(var_name) {
  50.                     if let Ok(new_value) = new_value.parse::<i32>() {
  51.                         *var_value = new_value;
  52.                     }
  53.                 }
  54.             }
  55.             Code::AddInto(var_name, add_value) => {
  56.                 if let Some(var_value) = integer_vars.get_mut(var_name) {
  57.                     if let Ok(add_value) = add_value.parse::<i32>() {
  58.                         *var_value += add_value;
  59.                     }
  60.                 }
  61.             }
  62.             Code::Print(var_name) => {
  63.                 if let Some(var_value) = integer_vars.get(var_name) {
  64.                     println!("{}", *var_value);
  65.                 }
  66.             }
  67.         }
  68.     }
  69. }
  70.  
  71. type CodeBlock = Vec<Code>;
  72.  
  73. type Str = &'static str;
  74.  
  75. enum Code {
  76.     Var(Str, Str),
  77.     Copy(Str, Str),
  78.     AddInto(Str, Str),
  79.     Print(Str),
  80. }
  81.  
Success #stdin #stdout 0s 4440KB
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https://ideone.com/x5Kmg9
language:
Rust (rust 1.56)
created:
4 years ago
visibility:
public

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