Add filter function

src/filter.rs

@@ -0,0 +1,75 @@
+use std::{
+    collections::HashMap,
+    io::{Read, Write},
+    str::FromStr,
+};
+
+pub enum Comparator<T: PartialOrd> {
+    EQUAL(T),
+    NOT_EQUAL(T),
+    GREATER_THAN(T),
+    LESS_THAN(T),
+    IN(Vec<T>),
+    NOT_IN(Vec<T>),
+}
+
+impl<T: PartialOrd> Comparator<T> {
+    pub fn is_valid(&self, value: T) -> bool {
+        match self {
+            Comparator::EQUAL(v) => value == *v,
+            Comparator::NOT_EQUAL(v) => value != *v,
+            Comparator::GREATER_THAN(v) => value > *v,
+            Comparator::LESS_THAN(v) => value < *v,
+            Comparator::IN(v) => v.contains(&value),
+            Comparator::NOT_IN(v) => !v.contains(&value),
+        }
+    }
+}
+
+pub trait FieldName {
+    // Name of the field this validator should work on
+    fn get_field_name(&self) -> String;
+}
+
+pub trait DataValidator: FieldName {
+    // Whether the given value is valid for the validator
+    fn is_valid(&self, s: &String) -> bool;
+}
+
+pub struct FilterRule<T: PartialOrd> {
+    column_name: String,
+    comparator: Comparator<T>,
+}
+
+impl<T: PartialOrd> FieldName for FilterRule<T> {
+    fn get_field_name(&self) -> String {
+        self.column_name.clone()
+    }
+}
+
+impl<T: FromStr + PartialOrd> DataValidator for FilterRule<T> {
+    fn is_valid(&self, s: &String) -> bool {
+        s.parse().map_or(false, |f| self.comparator.is_valid(f))
+    }
+}
+
+/**
+ * Write all lines from the input file to the output file, skipping records
+ * that don't satisfy the filter criteria
+ */
+pub fn filter_file(
+    rules: Vec<&dyn DataValidator>,
+    input: &mut csv::Reader<impl Read>,
+    output: &mut csv::Writer<impl Write>,
+) -> anyhow::Result<()> {
+    for line in input.deserialize() {
+        let line: HashMap<String, String> = line?;
+        if rules.iter().all(|rule| {
+            line.get(&rule.get_field_name())
+                .map_or(true, |value| rule.is_valid(value))
+        }) {
+            output.serialize(line)?;
+        }
+    }
+    Ok(())
+}

src/lib.rs

@@ -15,6 +15,8 @@ pub use self::shared_models::*;
 
 pub mod link;
 
+pub mod filter;
+
 #[no_mangle]
 pub extern "C" fn move_money_from_text(
     rules: *const c_char,