First implementation of the library

Signed-off-by: Max Lambrecht <[email protected]>

Author: maxlambrecht

Diff for: .github/workflows/ci.yml

@@ -0,0 +1,40 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: 'go.mod'
+
+      - name: Verify module dependencies
+        run: go mod tidy && git diff --exit-code
+
+      - name: Run go fmt
+        run: go fmt ./...
+
+      - name: Lint with golangci-lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          version: v1.64.8
+
+      - name: Run tests with coverage
+        run: go test -v -coverprofile=coverage.out ./...
+
+      - name: Upload Coverage to Coveralls
+        uses: coverallsapp/github-action@v2
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          path-to-lcov: coverage.out

Diff for: Makefile

@@ -0,0 +1,9 @@
+GO := go
+
+.PHONY: test
+test:
+	$(GO) test ./...
+
+.PHONY: deps
+deps:
+	$(GO) mod tidy

Diff for: README.md

@@ -1,2 +1,40 @@
-# odatasql
-Convert OData filter expressions to SQL WHERE clauses in Go.
+# ODataSQL - Convert OData Filters to SQL
+
+**ODataSQL** is a Go library that converts **OData filter expressions into SQL WHERE clauses** while preserving operator
+precedence.
+
+## 🔹 Usage
+
+```go
+func main() {
+    sql, err := odatasql.Convert("name eq 'Alice' and age gt 30")
+    if err != nil {
+        log.Fatal(err)
+    }
+    fmt.Println(sql) // Output: name = 'Alice' AND age > 30
+}
+```
+
+## 🛠 Supported Operators
+
+| OData | SQL   | Example OData                      | SQL Output                       |
+|-------|-------|------------------------------------|----------------------------------|
+| eq    | `=`   | `firtsName eq 'Bob'`               | `first_name = 'Bob'`             |
+| ne    | `!=`  | `status ne 'active'`               | `status != 'active'`             |
+| gt    | `>`   | `age gt 18`                        | `age > 18`                       |
+| ge    | `>=`  | `height ge 170`                    | `height >= 170`                  |
+| lt    | `<`   | `score lt 50`                      | `score < 50`                     |
+| le    | `<=`  | `price le 99.99`                   | `price <= 99.99`                 |
+| and   | `AND` | `age gt 18 and status eq 'active'` | `age > 18 AND status = 'active'` |
+| or    | `OR`  | `age lt 18 or premium eq true`     | `age < 18 OR premium = true`     |
+| not   | `NOT` | `not age gt 18`                    | `NOT age > 18`                   |
+| in    | `IN`  | `color in ('red', 'blue')`         | `color IN ('red', 'blue')`       |
+
+## 📂 Running Examples
+
+```sh
+go run examples/basic/basic.go
+go run examples/in_operator/in_operator.go
+go run examples/logical_operators/logical_operators.go
+go run examples/precedence/precedence.go
+```

Diff for: examples/basic/basic.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/maxlambrecht/odatasql"
+)
+
+// Basic example of converting an OData filter into an SQL WHERE clause.
+func main() {
+	sql, err := odatasql.Convert("name eq 'Alice' and age gt 30")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(sql)
+}

Diff for: examples/in_operator/in_operator.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	"github.com/maxlambrecht/odatasql"
+	"log"
+)
+
+func main() {
+	sql, err := odatasql.Convert("color in ('red', 'blue') and category eq 'electronics'")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(sql)
+}

Diff for: examples/logical_operators/logical_operators.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	"github.com/maxlambrecht/odatasql"
+	"log"
+)
+
+func main() {
+	sql, err := odatasql.Convert("age ge 30 or (status eq 'active' and premium eq true)")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(sql)
+}

Diff for: examples/precedence/precedence.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"fmt"
+	"github.com/maxlambrecht/odatasql"
+	"log"
+)
+
+// Demonstrates how operator precedence and explicit parentheses are preserved.
+func main() {
+	sql, err := odatasql.Convert("not (age gt 25 and status eq 'active') or premium eq true")
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(sql)
+}

Diff for: go.mod

@@ -0,0 +1,3 @@
+module github.com/maxlambrecht/odatasql
+
+go 1.24.1

Diff for: internal/ast.go

@@ -0,0 +1,81 @@
+package internal
+
+import (
+	"fmt"
+	"strings"
+)
+
+const (
+	opAnd = "AND"
+	opOr  = "OR"
+	opNot = "NOT"
+	opIn  = "IN"
+)
+
+// Node represents any part of the parsed expression.
+type Node interface {
+	// ToSQL generates the SQL snippet for the node.
+	// The level parameter indicates nesting for internal use.
+	ToSQL(level int) string
+}
+
+// BinaryNode represents an expression combining two subexpressions with "AND" or "OR".
+type BinaryNode struct {
+	Op          string // "AND" or "OR"
+	Left, Right Node
+}
+
+// ToSQL converts a BinaryNode to its SQL representation.
+func (b *BinaryNode) ToSQL(level int) string {
+	left := b.Left.ToSQL(level + 1)
+	right := b.Right.ToSQL(level + 1)
+	// For binary nodes, if not wrapped explicitly then add parentheses for nested expressions.
+	if level > 0 {
+		return fmt.Sprintf("(%s %s %s)", left, b.Op, right)
+	}
+	return fmt.Sprintf("%s %s %s", left, b.Op, right)
+}
+
+// NotNode represents a "NOT" operation.
+type NotNode struct {
+	Child Node
+}
+
+func (n *NotNode) ToSQL(level int) string {
+	child := n.Child.ToSQL(level + 1)
+	// For a NOT node, always add parentheses for nested expressions.
+	if level > 0 {
+		return fmt.Sprintf("(%s %s)", opNot, child)
+	}
+	return fmt.Sprintf("%s %s", opNot, child)
+}
+
+// ConditionNode represents a simple binary condition like "field = value".
+type ConditionNode struct {
+	Field, Op, Value string
+}
+
+func (c *ConditionNode) ToSQL(_ int) string {
+	return fmt.Sprintf("%s %s %s", c.Field, c.Op, c.Value)
+}
+
+// InNode represents an IN operator condition.
+type InNode struct {
+	Field  string
+	Values []string
+}
+
+func (i *InNode) ToSQL(_ int) string {
+	return fmt.Sprintf("%s %s (%s)", i.Field, opIn, strings.Join(i.Values, ", "))
+}
+
+// ParenNode represents an expression that was explicitly parenthesized in the input.
+type ParenNode struct {
+	Child Node
+}
+
+func (p *ParenNode) ToSQL(level int) string {
+	// Always emit the surrounding parentheses regardless of level.
+	// We call Child.ToSQL with level 0 so that inner nodes don't remove their grouping.
+	return fmt.Sprintf("(%s)", p.Child.ToSQL(0))
+}