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Update the cel/examples as well
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@TristonianJones
TristonianJones committed Jul 15, 2022
1 parent 7e3ee6c commit 7e855d6
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Showing 4 changed files with 79 additions and 95 deletions.
101 changes: 49 additions & 52 deletions examples/README.md
View file
Expand Up @@ -6,14 +6,13 @@ Evaluate expression `"Hello world! I'm " + name + "."` with `CEL` passed as
name.

```go
import (
"github.com/google/cel-go/cel"
"github.com/google/cel-go/checker/decls"
)

d := cel.Declarations(decls.NewVar("name", decls.String))
env, err := cel.NewEnv(d)
import "github.com/google/cel-go/cel"

env, err := cel.NewEnv(cel.Variable("name", cel.StringType))
// Check iss for compilation errors.
if err != nil {
log.Fatalln(err)
}
ast, iss := env.Compile(`"Hello world! I'm " + name + "."`)
// Check iss for compilation errors.
if iss.Err() != nil {
Expand All @@ -40,35 +39,31 @@ Evaluate expression `i.greet(you)` with:
```

First we need to declare two string variables and `greet` function.
`NewInstanceOverload` must be used if we want to declare function which will
operate on a type. First element of slice passed as `argTypes` into
`NewInstanceOverload` is declaration of instance type. Next elements are
parameters of function.
`Function` must be used if we want to declare an extension to CEL. The
`MemberOverload` declares an overload id, a list of arguments where the
first element the `argTypes` slice is the target type of the member
function. The remaining argument types are the signature of the member
method.

```go
decls.NewVar("i", decls.String),
decls.NewVar("you", decls.String),
decls.NewFunction("greet",
decls.NewInstanceOverload("string_greet_string",
[]*exprpb.Type{decls.String, decls.String},
decls.String))
... // Create env and compile
```

Let's implement `greet` function and pass it to `program`. We will be using
`Binary`, because `greet` function uses 2 parameters (1st instance, 2nd
function parameter).

```go
greetFunc := &functions.Overload{
Operator: "string_greet_string",
Binary: func(lhs ref.Val, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("Hello %s! Nice to meet you, I'm %s.\n", rhs, lhs))
}}
prg, err := env.Program(c, cel.Functions(greetFunc))

out, _, err := prg.Eval(map[string]interface{}{
env, _ := cel.NewEnv(
cel.Variable("i", cel.StringType),
cel.Variable("you", cel.StringType),
cel.Function("greet",
cel.MemberOverload("string_greet_string",
[]*cel.Type{cel.StringType, cel.StringType},
cel.StringType,
cel.BinaryBinding(func (lhs, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("Hello %s! Nice to meet you, I'm %s.\n", rhs, lhs))
},
),
),
),
)
// Create env and compile
prg, _ := env.Program(c)
out, _, _ := prg.Eval(map[string]interface{}{
"i": "CEL",
"you": "world",
})
Expand All @@ -87,26 +82,28 @@ Evaluate expression `shake_hands(i,you)` with:
shake_hands -> "%s and %s are shaking hands."
```

In order to declare global function we need to use `NewOverload`:
In order to declare global function we need to use `Overload` instead
of `MemberOverload` in the `Function` option:

```go
decls.NewVar("i", decls.String),
decls.NewVar("you", decls.String),
decls.NewFunction("shake_hands",
decls.NewOverload("shake_hands_string_string",
[]*exprpb.Type{decls.String, decls.String},
decls.String))
... // Create env and compile.

shakeFunc := &functions.Overload{
Operator: "shake_hands_string_string",
Binary: func(lhs ref.Val, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("%s and %s are shaking hands.\n", lhs, rhs))
}}
prg, err := env.Program(c, cel.Functions(shakeFunc))

out, _, err := prg.Eval(map[string]interface{}{
env, _ := cel.NewEnv(
cel.Variable("i", cel.StringType),
cel.Variable("you", cel.StringType),
cel.Function("shake_hands",
cel.Overload("shake_hands_string_string",
[]*cel.Type{cel.StringType, cel.StringType},
cel.StringType,
cel.BinaryBinding(func(lhs, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("%s and %s are shaking hands.\n", lhs, rhs))
},
),
),
),
)
// Create env and compile.
prg, _ := env.Program(c)
out, _, _ := prg.Eval(map[string]interface{}{
"i": "CEL",
"you": "world",
})
Expand Down
35 changes: 16 additions & 19 deletions examples/custom_global_function_test.go
View file
Expand Up @@ -19,23 +19,26 @@ import (
"log"

"github.com/google/cel-go/cel"
"github.com/google/cel-go/checker/decls"
"github.com/google/cel-go/common/types"
"github.com/google/cel-go/common/types/ref"
"github.com/google/cel-go/interpreter/functions"

exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
)

func ExampleCustomGlobalFunction() {
d := cel.Declarations(
decls.NewVar("i", decls.String),
decls.NewVar("you", decls.String),
decls.NewFunction("shake_hands",
decls.NewOverload("shake_hands_string_string",
[]*exprpb.Type{decls.String, decls.String},
decls.String)))
env, err := cel.NewEnv(d)
env, err := cel.NewEnv(
cel.Variable("i", cel.StringType),
cel.Variable("you", cel.StringType),
cel.Function("shake_hands",
cel.Overload("shake_hands_string_string",
[]*cel.Type{cel.StringType, cel.StringType},
cel.StringType,
cel.BinaryBinding(func(lhs, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("%s and %s are shaking hands.\n", lhs, rhs))
},
),
),
),
)
if err != nil {
log.Fatalf("environment creation error: %v\n", err)
}
Expand All @@ -44,13 +47,7 @@ func ExampleCustomGlobalFunction() {
if iss.Err() != nil {
log.Fatalln(iss.Err())
}
shakeFunc := &functions.Overload{
Operator: "shake_hands_string_string",
Binary: func(lhs ref.Val, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("%s and %s are shaking hands.\n", lhs, rhs))
}}
prg, err := env.Program(ast, cel.Functions(shakeFunc))
prg, err := env.Program(ast)
if err != nil {
log.Fatalf("Program creation error: %v\n", err)
}
Expand Down
34 changes: 13 additions & 21 deletions examples/custom_instance_function_test.go
View file
Expand Up @@ -19,12 +19,8 @@ import (
"log"

"github.com/google/cel-go/cel"
"github.com/google/cel-go/checker/decls"
"github.com/google/cel-go/common/types"
"github.com/google/cel-go/common/types/ref"
"github.com/google/cel-go/interpreter/functions"

exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
)

func ExampleCustomInstanceFunction() {
Expand Down Expand Up @@ -58,26 +54,22 @@ type customLib struct{}

func (customLib) CompileOptions() []cel.EnvOption {
return []cel.EnvOption{
cel.Declarations(
decls.NewVar("i", decls.String),
decls.NewVar("you", decls.String),
decls.NewFunction("greet",
decls.NewInstanceOverload("string_greet_string",
[]*exprpb.Type{decls.String, decls.String},
decls.String))),
}
}

func (customLib) ProgramOptions() []cel.ProgramOption {
return []cel.ProgramOption{
cel.Functions(
&functions.Overload{
Operator: "string_greet_string",
Binary: func(lhs ref.Val, rhs ref.Val) ref.Val {
cel.Variable("i", cel.StringType),
cel.Variable("you", cel.StringType),
cel.Function("greet",
cel.MemberOverload("string_greet_string",
[]*cel.Type{cel.StringType, cel.StringType},
cel.StringType,
cel.BinaryBinding(func(lhs, rhs ref.Val) ref.Val {
return types.String(
fmt.Sprintf("Hello %s! Nice to meet you, I'm %s.\n", rhs, lhs))
},
},
),
),
),
}
}

func (customLib) ProgramOptions() []cel.ProgramOption {
return []cel.ProgramOption{}
}
4 changes: 1 addition & 3 deletions examples/simple_test.go
View file
Expand Up @@ -19,12 +19,10 @@ import (
"log"

"github.com/google/cel-go/cel"
"github.com/google/cel-go/checker/decls"
)

func ExampleSimple() {
d := cel.Declarations(decls.NewVar("name", decls.String))
env, err := cel.NewEnv(d)
env, err := cel.NewEnv(cel.Variable("name", cel.StringType))
if err != nil {
log.Fatalf("environment creation error: %v\n", err)
}
Expand Down

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