refactor: change to offcial format parser #13

extensions/ext-computing/Cargo.toml

@@ -16,6 +16,8 @@ salsa = { git = "https://github.com/salsa-rs/salsa", package = "salsa-2022" }
 pest = "2.3.1"
 pest_derive = "2.3.1"
 
+lazy_static = "1.4.0"
+
 [dev-dependencies]
 actix-web = "4"
 tokio = { version = "1", features = ["full"] }

extensions/ext-computing/src/expr/grammar.pest

@@ -19,24 +19,24 @@
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
-program = _{ SOI ~ stmt ~ EOI }
+program     = _{ SOI ~ expr ~ EOI }
 
-stmt = _{ assign | expr }
-assign = { ident ~ "=" ~ expr }
-expr = { prefix* ~ atom ~ postfix* ~ (operation ~ atom)* }
-atom = _{ constants | function | ident | convert | num | "(" ~ expr ~ ")"  }
+stmt        = _{ assign | expr }
+assign      = { ident ~ "=" ~ expr }
+expr        = { prefix* ~ primary ~ postfix* ~ (infix ~ prefix* ~ primary ~ postfix* )* }
+primary     = _{ constants | function | ident | convert | num | "(" ~ expr ~ ")"  }
+infix       = _{ sub | add | mul | div | pow | percentOf | percentOn | rightShift | leftShift | modulus }
+prefix      = _{ neg }
+postfix     = _{ fac }
 
-operation = _{ sub | add | mul | div | pow | percentOf | percentOn | rightShift | leftShift | modulus }
 add         = { "+" | "with" | "plus" | "add" }
 sub         = { "-" | "without" | "subtract" | "minus" }
 mul         = { "*" | "times" | "multiply by" | "mul" }
 div         = { "/" | "divide by" | "divide" }
 pow         = { "^" | "power" }
 modulus     = { "%" | "mod" }
 
-prefix      =  _{ neg }
 neg         =   { "-" } // Negation
-postfix     =  _{ fac }
 fac         = { "!" } // Factorial
 rightShift  = { ">>" }
 
@@ -46,7 +46,6 @@ percentOn   = { "percent on" | "%" ~ "on" }
 
 function = { ident ~ "(" ~ expr ~ ")" }
 
-WHITESPACE = _{ " " | "\t" }
 ident = @{ ASCII_ALPHA ~ (ASCII_ALPHANUMERIC | "_")* ~ "'"* }
 int = { ("+" | "-")? ~ ASCII_DIGIT+ }
 num = @{ int ~ ("." ~ ASCII_DIGIT*)? ~ (^"e" ~ int)? }
@@ -155,3 +154,5 @@ YOTTABYTE = { "yottabytes" | "yottabyte"| ^"yb" }
 
 siunit = { AREA | DIGITALINFORMATION | SPEED | MASS | ANGLE  | TIME | LENGTH | TEMPERATURE  }
 convert = {  num ~ siunit ~  ( "to" | "as" | "in" ) ~ siunit }
+
+WHITESPACE   =  _{ " " | "\t" | NEWLINE }

extensions/ext-computing/src/expr/parser.rs

@@ -6,35 +6,35 @@ use pest::pratt_parser::*;
 #[grammar = "expr/grammar.pest"]
 struct Calculator;
 
+lazy_static! {
+    static ref PRATT_PARSER: PrattParser<Rule> = {
+        // Precedence is defined lowest to highest
+        PrattParser::new()
+          .op(Op::infix(Rule::add, Assoc::Left) | Op::infix(Rule::sub, Assoc::Left))
+          .op(Op::infix(Rule::mul, Assoc::Left) | Op::infix(Rule::div, Assoc::Left))
+          .op(Op::infix(Rule::pow, Assoc::Right))
+          .op(Op::postfix(Rule::fac))
+          .op(Op::prefix(Rule::neg))
+    };
+}
+
 pub fn parse(input: &str) -> f64 {
-  let parse_result = Calculator::parse(Rule::program, input);
-  match parse_result {
-    Ok(r) => eval(r),
+  match Calculator::parse(Rule::program, input) {
+    Ok(mut pairs) => parse_expr(pairs.next().unwrap().into_inner()),
     Err(_) => f64::NAN,
   }
 }
 
-fn eval(pairs: Pairs<Rule>) -> f64 {
-  let pratt =
-    PrattParser::new()
-      .op(Op::infix(Rule::add, Assoc::Left) | Op::infix(Rule::sub, Assoc::Left))
-      .op(Op::infix(Rule::mul, Assoc::Left) | Op::infix(Rule::div, Assoc::Left))
-      .op(Op::infix(Rule::pow, Assoc::Right))
-      .op(Op::postfix(Rule::fac))
-      .op(Op::prefix(Rule::neg));
-
-  parse_expr(pairs, &pratt)
-}
-
-fn parse_expr(pairs: Pairs<Rule>, pratt: &PrattParser<Rule>) -> f64 {
-  pratt
+// can be follow: <https://github.com/pest-parser/book/blob/master/examples/pest-calculator/src/main.rs>
+fn parse_expr(pairs: Pairs<Rule>) -> f64 {
+  PRATT_PARSER
     .map_primary(|primary| match primary.as_rule() {
+      Rule::expr => parse_expr(primary.into_inner()),
       Rule::int => primary.as_str().parse().unwrap(),
-      Rule::expr => parse_expr(primary.into_inner(), pratt), // from "(" ~ expr ~ ")"
       Rule::num => primary.as_str().parse().unwrap(),
       _ => panic!("unimplemented, {:?}", primary.as_rule()),
     })
-    .map_prefix(|op, rhs| match op.as_rule() {
+    .map_prefix(|op, rhs: f64| match op.as_rule() {
       Rule::neg => -rhs,
       _ => panic!("unimplemented, {:?}", op.as_rule()),
     })
@@ -58,14 +58,13 @@ mod tests {
   use super::*;
 
   #[test]
-  #[ignore]
   fn it_works() {
     assert_eq!(parse("1 + 2"), 3.0);
-    // assert_eq!(parse("1 + 2 * 3"), 7.0);
-    // assert_eq!(parse("(1 + 2) * 3"), 9.0);
-    // assert_eq!(parse("1 + 2 * 3 + 4"), 11.0);
-    // assert_eq!(parse("1 + 2 * (3 + 4)"), 15.0);
-    // assert_eq!(parse("1 + 2 * (3 + 4) / 5"), 3.0);
-    // assert_eq!(parse("1 + 2 * (3 + 4) / 5 - 6"), -3.0);
+    assert_eq!(parse("1 + 2 * 3"), 7.0);
+    assert_eq!(parse("(1 + 2) * 3"), 9.0);
+    assert_eq!(parse("1 + 2 * 3 + 4"), 11.0);
+    assert_eq!(parse("1 + 2 * (3 + 4)"), 15.0);
+    assert_eq!(parse("1 + 2 * (3 + 4) / 5"), 3.0);
+    assert_eq!(parse("1 + 2 * (3 + 4) / 5 - 6"), -3.0);
   }
 }

extensions/ext-computing/src/lib.rs

@@ -1,3 +1,6 @@
+#[macro_use]
+extern crate lazy_static;
+
 extern crate pest;
 #[macro_use]
 extern crate pest_derive;