Function call lowering and evaluation for selected built-ins (#264)

Function call lowering and evaluation for selected built-ins:
- char_len
- lower
- upper
- substring
- trim
- coalesce
- nullif
- exists

partiql-eval/src/eval.rs

@@ -1099,3 +1099,217 @@ impl EvalContext for BasicContext {
         &self.bindings
     }
 }
+
+#[inline]
+#[track_caller]
+fn string_transform<FnTransform>(value: Value, transform_fn: FnTransform) -> Value
+where
+    FnTransform: Fn(&str) -> Value,
+{
+    match value {
+        Null => Value::Null,
+        Value::String(s) => transform_fn(s.as_ref()),
+        _ => Value::Missing,
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnLower {
+    pub value: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnLower {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        string_transform(self.value.evaluate(bindings, ctx), |s| {
+            s.to_lowercase().into()
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnUpper {
+    pub value: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnUpper {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        string_transform(self.value.evaluate(bindings, ctx), |s| {
+            s.to_uppercase().into()
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnCharLength {
+    pub value: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnCharLength {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        string_transform(self.value.evaluate(bindings, ctx), |s| {
+            s.chars().count().into()
+        })
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnSubstring {
+    pub value: Box<dyn EvalExpr>,
+    pub offset: Box<dyn EvalExpr>,
+    pub length: Option<Box<dyn EvalExpr>>,
+}
+
+impl EvalExpr for EvalFnSubstring {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        let value = match self.value.evaluate(bindings, ctx) {
+            Null => None,
+            Value::String(s) => Some(s),
+            _ => return Value::Missing,
+        };
+        let offset = match self.offset.evaluate(bindings, ctx) {
+            Null => None,
+            Value::Integer(i) => Some(i),
+            _ => return Value::Missing,
+        };
+
+        if let Some(length) = &self.length {
+            let length = match length.evaluate(bindings, ctx) {
+                Value::Integer(i) => i as usize,
+                Value::Null => return Value::Null,
+                _ => return Value::Missing,
+            };
+            if let (Some(value), Some(offset)) = (value, offset) {
+                let (offset, length) = if length < 1 {
+                    (0, 0)
+                } else if offset < 1 {
+                    let length = std::cmp::max(offset + (length - 1) as i64, 0) as usize;
+                    let offset = std::cmp::max(offset, 0) as usize;
+                    (offset, length)
+                } else {
+                    ((offset - 1) as usize, length)
+                };
+                value
+                    .chars()
+                    .skip(offset)
+                    .take(length)
+                    .collect::<String>()
+                    .into()
+            } else {
+                // either value or offset was NULL; return NULL
+                Value::Null
+            }
+        } else if let (Some(value), Some(offset)) = (value, offset) {
+            let offset = (std::cmp::max(offset, 1) - 1) as usize;
+            value.chars().skip(offset).collect::<String>().into()
+        } else {
+            // either value or offset was NULL; return NULL
+            Value::Null
+        }
+    }
+}
+
+#[inline]
+#[track_caller]
+fn trim<FnTrim>(value: Value, to_trim: Value, trim_fn: FnTrim) -> Value
+where
+    FnTrim: Fn(&str, &str) -> Value,
+{
+    let value = match value {
+        Value::String(s) => Some(s),
+        Null => None,
+        _ => return Value::Missing,
+    };
+    let to_trim = match to_trim {
+        Value::String(s) => s,
+        Null => return Value::Null,
+        _ => return Value::Missing,
+    };
+    if let Some(s) = value {
+        trim_fn(&s, &to_trim)
+    } else {
+        Value::Null
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnBtrim {
+    pub value: Box<dyn EvalExpr>,
+    pub to_trim: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnBtrim {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        trim(
+            self.value.evaluate(bindings, ctx),
+            self.to_trim.evaluate(bindings, ctx),
+            |s, to_trim| {
+                let to_trim = to_trim.chars().collect_vec();
+                s.trim_matches(&to_trim[..]).into()
+            },
+        )
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnRtrim {
+    pub value: Box<dyn EvalExpr>,
+    pub to_trim: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnRtrim {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        trim(
+            self.value.evaluate(bindings, ctx),
+            self.to_trim.evaluate(bindings, ctx),
+            |s, to_trim| {
+                let to_trim = to_trim.chars().collect_vec();
+                s.trim_end_matches(&to_trim[..]).into()
+            },
+        )
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnLtrim {
+    pub value: Box<dyn EvalExpr>,
+    pub to_trim: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnLtrim {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        trim(
+            self.value.evaluate(bindings, ctx),
+            self.to_trim.evaluate(bindings, ctx),
+            |s, to_trim| {
+                let to_trim = to_trim.chars().collect_vec();
+                s.trim_start_matches(&to_trim[..]).into()
+            },
+        )
+    }
+}
+
+#[derive(Debug)]
+pub struct EvalFnExists {
+    pub value: Box<dyn EvalExpr>,
+}
+
+impl EvalExpr for EvalFnExists {
+    #[inline]
+    fn evaluate(&self, bindings: &Tuple, ctx: &dyn EvalContext) -> Value {
+        let value = self.value.evaluate(bindings, ctx);
+        let exists = match value {
+            Value::Bag(b) => !b.is_empty(),
+            Value::List(l) => !l.is_empty(),
+            Value::Tuple(t) => !t.is_empty(),
+            _ => false,
+        };
+        Value::Boolean(exists)
+    }
+}

partiql-eval/src/plan.rs

@@ -4,16 +4,17 @@ use std::collections::HashMap;
 
 use partiql_logical as logical;
 use partiql_logical::{
-    BinaryOp, BindingsOp, IsTypeExpr, JoinKind, LogicalPlan, OpId, PathComponent, Pattern,
-    PatternMatchExpr, SearchedCase, Type, UnaryOp, ValueExpr,
+    BinaryOp, BindingsOp, CallName, IsTypeExpr, JoinKind, LogicalPlan, OpId, PathComponent,
+    Pattern, PatternMatchExpr, SearchedCase, Type, UnaryOp, ValueExpr,
 };
 
 use crate::eval;
 use crate::eval::{
     EvalBagExpr, EvalBetweenExpr, EvalBinOp, EvalBinOpExpr, EvalDynamicLookup, EvalExpr,
-    EvalIsTypeExpr, EvalJoinKind, EvalLikeMatch, EvalListExpr, EvalLitExpr, EvalPath, EvalPlan,
-    EvalSearchedCaseExpr, EvalSubQueryExpr, EvalTupleExpr, EvalUnaryOp, EvalUnaryOpExpr,
-    EvalVarRef, Evaluable,
+    EvalFnBtrim, EvalFnCharLength, EvalFnExists, EvalFnLower, EvalFnLtrim, EvalFnRtrim,
+    EvalFnSubstring, EvalFnUpper, EvalIsTypeExpr, EvalJoinKind, EvalLikeMatch, EvalListExpr,
+    EvalLitExpr, EvalPath, EvalPlan, EvalSearchedCaseExpr, EvalSubQueryExpr, EvalTupleExpr,
+    EvalUnaryOp, EvalUnaryOpExpr, EvalVarRef, Evaluable,
 };
 use crate::pattern_match::like_to_re_pattern;
 use partiql_value::Value::Null;
@@ -337,6 +338,73 @@ impl EvaluatorPlanner {
 
                 Box::new(EvalDynamicLookup { lookups })
             }
+            ValueExpr::Call(logical::CallExpr { name, arguments }) => {
+                let mut args = arguments
+                    .into_iter()
+                    .map(|arg| self.plan_values(arg))
+                    .collect_vec();
+                match name {
+                    CallName::Lower => {
+                        assert_eq!(args.len(), 1);
+                        Box::new(EvalFnLower {
+                            value: args.pop().unwrap(),
+                        })
+                    }
+                    CallName::Upper => {
+                        assert_eq!(args.len(), 1);
+                        Box::new(EvalFnUpper {
+                            value: args.pop().unwrap(),
+                        })
+                    }
+                    CallName::CharLength => {
+                        assert_eq!(args.len(), 1);
+                        Box::new(EvalFnCharLength {
+                            value: args.pop().unwrap(),
+                        })
+                    }
+                    CallName::LTrim => {
+                        assert_eq!(args.len(), 2);
+                        let value = args.pop().unwrap();
+                        let to_trim = args.pop().unwrap();
+                        Box::new(EvalFnLtrim { value, to_trim })
+                    }
+                    CallName::BTrim => {
+                        assert_eq!(args.len(), 2);
+                        let value = args.pop().unwrap();
+                        let to_trim = args.pop().unwrap();
+                        Box::new(EvalFnBtrim { value, to_trim })
+                    }
+                    CallName::RTrim => {
+                        assert_eq!(args.len(), 2);
+                        let value = args.pop().unwrap();
+                        let to_trim = args.pop().unwrap();
+                        Box::new(EvalFnRtrim { value, to_trim })
+                    }
+                    CallName::Substring => {
+                        assert!((2usize..=3).contains(&args.len()));
+
+                        let length = if args.len() == 3 {
+                            Some(args.pop().unwrap())
+                        } else {
+                            None
+                        };
+                        let offset = args.pop().unwrap();
+                        let value = args.pop().unwrap();
+
+                        Box::new(EvalFnSubstring {
+                            value,
+                            offset,
+                            length,
+                        })
+                    }
+                    CallName::Exists => {
+                        assert_eq!(args.len(), 1);
+                        Box::new(EvalFnExists {
+                            value: args.pop().unwrap(),
+                        })
+                    }
+                }
+            }
         }
     }
 }