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-rw-r--r--modules/templates/eval/eval.go344
-rw-r--r--modules/templates/eval/eval_test.go94
2 files changed, 438 insertions, 0 deletions
diff --git a/modules/templates/eval/eval.go b/modules/templates/eval/eval.go
new file mode 100644
index 0000000..5d4ac91
--- /dev/null
+++ b/modules/templates/eval/eval.go
@@ -0,0 +1,344 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package eval
+
+import (
+ "fmt"
+ "strconv"
+ "strings"
+
+ "code.gitea.io/gitea/modules/util"
+)
+
+type Num struct {
+ Value any // int64 or float64, nil on error
+}
+
+var opPrecedence = map[string]int{
+ // "(": 1, this is for low precedence like function calls, they are handled separately
+ "or": 2,
+ "and": 3,
+ "not": 4,
+ "==": 5, "!=": 5, "<": 5, "<=": 5, ">": 5, ">=": 5,
+ "+": 6, "-": 6,
+ "*": 7, "/": 7,
+}
+
+type stack[T any] struct {
+ name string
+ elems []T
+}
+
+func (s *stack[T]) push(t T) {
+ s.elems = append(s.elems, t)
+}
+
+func (s *stack[T]) pop() T {
+ if len(s.elems) == 0 {
+ panic(s.name + " stack is empty")
+ }
+ t := s.elems[len(s.elems)-1]
+ s.elems = s.elems[:len(s.elems)-1]
+ return t
+}
+
+func (s *stack[T]) peek() T {
+ if len(s.elems) == 0 {
+ panic(s.name + " stack is empty")
+ }
+ return s.elems[len(s.elems)-1]
+}
+
+type operator string
+
+type eval struct {
+ stackNum stack[Num]
+ stackOp stack[operator]
+ funcMap map[string]func([]Num) Num
+}
+
+func newEval() *eval {
+ e := &eval{}
+ e.stackNum.name = "num"
+ e.stackOp.name = "op"
+ return e
+}
+
+func toNum(v any) (Num, error) {
+ switch v := v.(type) {
+ case string:
+ if strings.Contains(v, ".") {
+ n, err := strconv.ParseFloat(v, 64)
+ if err != nil {
+ return Num{n}, err
+ }
+ return Num{n}, nil
+ }
+ n, err := strconv.ParseInt(v, 10, 64)
+ if err != nil {
+ return Num{n}, err
+ }
+ return Num{n}, nil
+ case float32, float64:
+ n, _ := util.ToFloat64(v)
+ return Num{n}, nil
+ default:
+ n, err := util.ToInt64(v)
+ if err != nil {
+ return Num{n}, err
+ }
+ return Num{n}, nil
+ }
+}
+
+func truth(b bool) int64 {
+ if b {
+ return int64(1)
+ }
+ return int64(0)
+}
+
+func applyOp2Generic[T int64 | float64](op operator, n1, n2 T) Num {
+ switch op {
+ case "+":
+ return Num{n1 + n2}
+ case "-":
+ return Num{n1 - n2}
+ case "*":
+ return Num{n1 * n2}
+ case "/":
+ return Num{n1 / n2}
+ case "==":
+ return Num{truth(n1 == n2)}
+ case "!=":
+ return Num{truth(n1 != n2)}
+ case "<":
+ return Num{truth(n1 < n2)}
+ case "<=":
+ return Num{truth(n1 <= n2)}
+ case ">":
+ return Num{truth(n1 > n2)}
+ case ">=":
+ return Num{truth(n1 >= n2)}
+ case "and":
+ t1, _ := util.ToFloat64(n1)
+ t2, _ := util.ToFloat64(n2)
+ return Num{truth(t1 != 0 && t2 != 0)}
+ case "or":
+ t1, _ := util.ToFloat64(n1)
+ t2, _ := util.ToFloat64(n2)
+ return Num{truth(t1 != 0 || t2 != 0)}
+ }
+ panic("unknown operator: " + string(op))
+}
+
+func applyOp2(op operator, n1, n2 Num) Num {
+ float := false
+ if _, ok := n1.Value.(float64); ok {
+ float = true
+ } else if _, ok = n2.Value.(float64); ok {
+ float = true
+ }
+ if float {
+ f1, _ := util.ToFloat64(n1.Value)
+ f2, _ := util.ToFloat64(n2.Value)
+ return applyOp2Generic(op, f1, f2)
+ }
+ return applyOp2Generic(op, n1.Value.(int64), n2.Value.(int64))
+}
+
+func toOp(v any) (operator, error) {
+ if v, ok := v.(string); ok {
+ return operator(v), nil
+ }
+ return "", fmt.Errorf(`unsupported token type "%T"`, v)
+}
+
+func (op operator) hasOpenBracket() bool {
+ return strings.HasSuffix(string(op), "(") // it's used to support functions like "sum("
+}
+
+func (op operator) isComma() bool {
+ return op == ","
+}
+
+func (op operator) isCloseBracket() bool {
+ return op == ")"
+}
+
+type ExprError struct {
+ msg string
+ tokens []any
+ err error
+}
+
+func (err ExprError) Error() string {
+ sb := strings.Builder{}
+ sb.WriteString(err.msg)
+ sb.WriteString(" [ ")
+ for _, token := range err.tokens {
+ _, _ = fmt.Fprintf(&sb, `"%v" `, token)
+ }
+ sb.WriteString("]")
+ if err.err != nil {
+ sb.WriteString(": ")
+ sb.WriteString(err.err.Error())
+ }
+ return sb.String()
+}
+
+func (err ExprError) Unwrap() error {
+ return err.err
+}
+
+func (e *eval) applyOp() {
+ op := e.stackOp.pop()
+ if op == "not" {
+ num := e.stackNum.pop()
+ i, _ := util.ToInt64(num.Value)
+ e.stackNum.push(Num{truth(i == 0)})
+ } else if op.hasOpenBracket() || op.isCloseBracket() || op.isComma() {
+ panic(fmt.Sprintf("incomplete sub-expression with operator %q", op))
+ } else {
+ num2 := e.stackNum.pop()
+ num1 := e.stackNum.pop()
+ e.stackNum.push(applyOp2(op, num1, num2))
+ }
+}
+
+func (e *eval) exec(tokens ...any) (ret Num, err error) {
+ defer func() {
+ if r := recover(); r != nil {
+ rErr, ok := r.(error)
+ if !ok {
+ rErr = fmt.Errorf("%v", r)
+ }
+ err = ExprError{"invalid expression", tokens, rErr}
+ }
+ }()
+ for _, token := range tokens {
+ n, err := toNum(token)
+ if err == nil {
+ e.stackNum.push(n)
+ continue
+ }
+
+ op, err := toOp(token)
+ if err != nil {
+ return Num{}, ExprError{"invalid expression", tokens, err}
+ }
+
+ switch {
+ case op.hasOpenBracket():
+ e.stackOp.push(op)
+ case op.isCloseBracket(), op.isComma():
+ var stackTopOp operator
+ for len(e.stackOp.elems) > 0 {
+ stackTopOp = e.stackOp.peek()
+ if stackTopOp.hasOpenBracket() || stackTopOp.isComma() {
+ break
+ }
+ e.applyOp()
+ }
+ if op.isCloseBracket() {
+ nums := []Num{e.stackNum.pop()}
+ for !e.stackOp.peek().hasOpenBracket() {
+ stackTopOp = e.stackOp.pop()
+ if !stackTopOp.isComma() {
+ return Num{}, ExprError{"bracket doesn't match", tokens, nil}
+ }
+ nums = append(nums, e.stackNum.pop())
+ }
+ for i, j := 0, len(nums)-1; i < j; i, j = i+1, j-1 {
+ nums[i], nums[j] = nums[j], nums[i] // reverse nums slice, to get the right order for arguments
+ }
+ stackTopOp = e.stackOp.pop()
+ fn := string(stackTopOp[:len(stackTopOp)-1])
+ if fn == "" {
+ if len(nums) != 1 {
+ return Num{}, ExprError{"too many values in one bracket", tokens, nil}
+ }
+ e.stackNum.push(nums[0])
+ } else if f, ok := e.funcMap[fn]; ok {
+ e.stackNum.push(f(nums))
+ } else {
+ return Num{}, ExprError{"unknown function: " + fn, tokens, nil}
+ }
+ } else {
+ e.stackOp.push(op)
+ }
+ default:
+ for len(e.stackOp.elems) > 0 && len(e.stackNum.elems) > 0 {
+ stackTopOp := e.stackOp.peek()
+ if stackTopOp.hasOpenBracket() || stackTopOp.isComma() || precedence(stackTopOp, op) < 0 {
+ break
+ }
+ e.applyOp()
+ }
+ e.stackOp.push(op)
+ }
+ }
+ for len(e.stackOp.elems) > 0 && !e.stackOp.peek().isComma() {
+ e.applyOp()
+ }
+ if len(e.stackNum.elems) != 1 {
+ return Num{}, ExprError{fmt.Sprintf("expect 1 value as final result, but there are %d", len(e.stackNum.elems)), tokens, nil}
+ }
+ return e.stackNum.pop(), nil
+}
+
+func precedence(op1, op2 operator) int {
+ p1 := opPrecedence[string(op1)]
+ p2 := opPrecedence[string(op2)]
+ if p1 == 0 {
+ panic("unknown operator precedence: " + string(op1))
+ } else if p2 == 0 {
+ panic("unknown operator precedence: " + string(op2))
+ }
+ return p1 - p2
+}
+
+func castFloat64(nums []Num) bool {
+ hasFloat := false
+ for _, num := range nums {
+ if _, hasFloat = num.Value.(float64); hasFloat {
+ break
+ }
+ }
+ if hasFloat {
+ for i, num := range nums {
+ if _, ok := num.Value.(float64); !ok {
+ f, _ := util.ToFloat64(num.Value)
+ nums[i] = Num{f}
+ }
+ }
+ }
+ return hasFloat
+}
+
+func fnSum(nums []Num) Num {
+ if castFloat64(nums) {
+ var sum float64
+ for _, num := range nums {
+ sum += num.Value.(float64)
+ }
+ return Num{sum}
+ }
+ var sum int64
+ for _, num := range nums {
+ sum += num.Value.(int64)
+ }
+ return Num{sum}
+}
+
+// Expr evaluates the given expression tokens and returns the result.
+// It supports the following operators: +, -, *, /, and, or, not, ==, !=, >, >=, <, <=.
+// Non-zero values are treated as true, zero values are treated as false.
+// If no error occurs, the result is either an int64 or a float64.
+// If all numbers are integer, the result is an int64, otherwise if there is any float number, the result is a float64.
+func Expr(tokens ...any) (Num, error) {
+ e := newEval()
+ e.funcMap = map[string]func([]Num) Num{"sum": fnSum}
+ return e.exec(tokens...)
+}
diff --git a/modules/templates/eval/eval_test.go b/modules/templates/eval/eval_test.go
new file mode 100644
index 0000000..3e68203
--- /dev/null
+++ b/modules/templates/eval/eval_test.go
@@ -0,0 +1,94 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package eval
+
+import (
+ "math"
+ "strings"
+ "testing"
+
+ "github.com/stretchr/testify/assert"
+ "github.com/stretchr/testify/require"
+)
+
+func tokens(s string) (a []any) {
+ for _, v := range strings.Fields(s) {
+ a = append(a, v)
+ }
+ return a
+}
+
+func TestEval(t *testing.T) {
+ n, err := Expr(0, "/", 0.0)
+ require.NoError(t, err)
+ assert.True(t, math.IsNaN(n.Value.(float64)))
+
+ _, err = Expr(nil)
+ require.ErrorContains(t, err, "unsupported token type")
+ _, err = Expr([]string{})
+ require.ErrorContains(t, err, "unsupported token type")
+ _, err = Expr(struct{}{})
+ require.ErrorContains(t, err, "unsupported token type")
+
+ cases := []struct {
+ expr string
+ want any
+ }{
+ {"-1", int64(-1)},
+ {"1 + 2", int64(3)},
+ {"3 - 2 + 4", int64(5)},
+ {"1 + 2 * 3", int64(7)},
+ {"1 + ( 2 * 3 )", int64(7)},
+ {"( 1 + 2 ) * 3", int64(9)},
+ {"( 1 + 2.0 ) / 3", float64(1)},
+ {"sum( 1 , 2 , 3 , 4 )", int64(10)},
+ {"100 + sum( 1 , 2 + 3 , 0.0 ) / 2", float64(103)},
+ {"100 * 5 / ( 5 + 15 )", int64(25)},
+ {"9 == 5", int64(0)},
+ {"5 == 5", int64(1)},
+ {"9 != 5", int64(1)},
+ {"5 != 5", int64(0)},
+ {"9 > 5", int64(1)},
+ {"5 > 9", int64(0)},
+ {"5 >= 9", int64(0)},
+ {"9 >= 9", int64(1)},
+ {"9 < 5", int64(0)},
+ {"5 < 9", int64(1)},
+ {"9 <= 5", int64(0)},
+ {"5 <= 5", int64(1)},
+ {"1 and 2", int64(1)}, // Golang template definition: non-zero values are all truth
+ {"1 and 0", int64(0)},
+ {"0 and 0", int64(0)},
+ {"1 or 2", int64(1)},
+ {"1 or 0", int64(1)},
+ {"0 or 1", int64(1)},
+ {"0 or 0", int64(0)},
+ {"not 2 == 1", int64(1)},
+ {"not not ( 9 < 5 )", int64(0)},
+ }
+
+ for _, c := range cases {
+ n, err := Expr(tokens(c.expr)...)
+ require.NoError(t, err, "expr: %s", c.expr)
+ assert.Equal(t, c.want, n.Value)
+ }
+
+ bads := []struct {
+ expr string
+ errMsg string
+ }{
+ {"0 / 0", "integer divide by zero"},
+ {"1 +", "num stack is empty"},
+ {"+ 1", "num stack is empty"},
+ {"( 1", "incomplete sub-expression"},
+ {"1 )", "op stack is empty"}, // can not find the corresponding open bracket after the stack becomes empty
+ {"1 , 2", "expect 1 value as final result"},
+ {"( 1 , 2 )", "too many values in one bracket"},
+ {"1 a 2", "unknown operator"},
+ }
+ for _, c := range bads {
+ _, err = Expr(tokens(c.expr)...)
+ require.ErrorContains(t, err, c.errMsg, "expr: %s", c.expr)
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 19:59:56 +0100