101 lines
2.9 KiB
Go
101 lines
2.9 KiB
Go
/*
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* Salix - Go templating engine
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* Copyright (C) 2023 Elara Musayelyan
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package salix
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import (
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"bytes"
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"io"
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"go.elara.ws/salix/ast"
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)
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// Tag represents a tag in a Salix template
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type Tag interface {
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Run(tc *TagContext, block, args []ast.Node) error
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}
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var globalTags = map[string]Tag{
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"if": ifTag{},
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"for": forTag{},
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"include": includeTag{},
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"macro": macroTag{},
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}
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// TagContext is passed to Tag implementations to allow them to control the interpreter
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type TagContext struct {
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Tag ast.Tag
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w io.Writer
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t *Template
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local map[string]any
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}
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// Execute runs the interpreter on the given AST nodes, with the given local variables.
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func (tc *TagContext) Execute(nodes []ast.Node, local map[string]any) error {
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return tc.t.execute(tc.w, nodes, mergeMap(tc.local, local))
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}
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// ExecuteToMemory runs the interpreter on the given AST nodes, with the given local variables, and
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// returns the resulting bytes rather than writing them out.
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func (tc *TagContext) ExecuteToMemory(nodes []ast.Node, local map[string]any) ([]byte, error) {
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buf := &bytes.Buffer{}
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err := tc.t.execute(buf, nodes, mergeMap(tc.local, local))
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if err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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// GetValue evaluates the given AST node using the given local variables.
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func (tc *TagContext) GetValue(node ast.Node, local map[string]any) (any, error) {
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return tc.t.getValue(node, mergeMap(tc.local, local))
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}
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// PosError returns an error with the file position prepended. This should be used
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// for errors wherever possible, to make it easier for users to find errors.
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func (tc *TagContext) PosError(node ast.Node, format string, v ...any) error {
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return ast.PosError(node, format, v...)
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}
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// NodeToString returns a textual representation of the given AST node for users to see,
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// such as in error messages. This does not directly correlate to Salix source code.
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func (tc *TagContext) NodeToString(node ast.Node) string {
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return valueToString(node)
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}
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// Write writes b to the underlying writer. It implements
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// the io.Writer interface.
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func (tc *TagContext) Write(b []byte) (int, error) {
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return tc.w.Write(b)
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}
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func mergeMap(a, b map[string]any) map[string]any {
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out := map[string]any{}
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if a != nil {
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for k, v := range a {
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out[k] = v
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}
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}
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if b != nil {
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for k, v := range b {
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out[k] = v
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}
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}
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return out
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}
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