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2e81e301ae
There was inconsistency between variables used for function definitions in HCL and JSON format. Updated JSON to match HCL, fixed documentation and removed the unused code from userfunc pkg (based on HCL upstream) to avoid confusion. Theoretically we could add some temporary backwards compatibility for the JSON format but I think it is unlikely that someone uses JSON format for this and also defined variadic parameters. Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
104 lines
3.2 KiB
Go
104 lines
3.2 KiB
Go
package userfunc
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import (
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"github.com/hashicorp/hcl/v2"
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"github.com/zclconf/go-cty/cty"
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"github.com/zclconf/go-cty/cty/function"
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)
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// A ContextFunc is a callback used to produce the base EvalContext for
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// running a particular set of functions.
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//
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// This is a function rather than an EvalContext directly to allow functions
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// to be decoded before their context is complete. This will be true, for
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// example, for applications that wish to allow functions to refer to themselves.
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//
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// The simplest use of a ContextFunc is to give user functions access to the
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// same global variables and functions available elsewhere in an application's
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// configuration language, but more complex applications may use different
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// contexts to support lexical scoping depending on where in a configuration
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// structure a function declaration is found, etc.
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type ContextFunc func() *hcl.EvalContext
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// NewFunction creates a new function instance from preparsed HCL expressions.
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func NewFunction(paramsExpr, varParamExpr, resultExpr hcl.Expression, getBaseCtx func() *hcl.EvalContext) (function.Function, hcl.Diagnostics) {
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var params []string
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var varParam string
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paramExprs, paramsDiags := hcl.ExprList(paramsExpr)
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if paramsDiags.HasErrors() {
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return function.Function{}, paramsDiags
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}
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for _, paramExpr := range paramExprs {
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param := hcl.ExprAsKeyword(paramExpr)
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if param == "" {
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return function.Function{}, hcl.Diagnostics{{
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Severity: hcl.DiagError,
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Summary: "Invalid param element",
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Detail: "Each parameter name must be an identifier.",
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Subject: paramExpr.Range().Ptr(),
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}}
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}
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params = append(params, param)
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}
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if varParamExpr != nil {
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varParam = hcl.ExprAsKeyword(varParamExpr)
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if varParam == "" {
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return function.Function{}, hcl.Diagnostics{{
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Severity: hcl.DiagError,
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Summary: "Invalid variadic_params",
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Detail: "The variadic parameter name must be an identifier.",
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Subject: varParamExpr.Range().Ptr(),
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}}
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}
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}
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spec := &function.Spec{}
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for _, paramName := range params {
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spec.Params = append(spec.Params, function.Parameter{
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Name: paramName,
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Type: cty.DynamicPseudoType,
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})
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}
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if varParamExpr != nil {
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spec.VarParam = &function.Parameter{
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Name: varParam,
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Type: cty.DynamicPseudoType,
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}
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}
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impl := func(args []cty.Value) (cty.Value, error) {
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ctx := getBaseCtx()
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ctx = ctx.NewChild()
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ctx.Variables = make(map[string]cty.Value)
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// The cty function machinery guarantees that we have at least
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// enough args to fill all of our params.
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for i, paramName := range params {
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ctx.Variables[paramName] = args[i]
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}
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if spec.VarParam != nil {
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varArgs := args[len(params):]
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ctx.Variables[varParam] = cty.TupleVal(varArgs)
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}
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result, diags := resultExpr.Value(ctx)
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if diags.HasErrors() {
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// Smuggle the diagnostics out via the error channel, since
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// a diagnostics sequence implements error. Caller can
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// type-assert this to recover the individual diagnostics
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// if desired.
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return cty.DynamicVal, diags
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}
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return result, nil
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}
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spec.Type = func(args []cty.Value) (cty.Type, error) {
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val, err := impl(args)
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return val.Type(), err
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}
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spec.Impl = func(args []cty.Value, retType cty.Type) (cty.Value, error) {
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return impl(args)
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}
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return function.New(spec), nil
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}
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