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author | Matt Holt <mholt@users.noreply.github.com> | 2019-08-21 11:28:03 -0600 |
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committer | GitHub <noreply@github.com> | 2019-08-21 11:28:03 -0600 |
commit | 0544f0266a11874efb305a46db762248e64bc62d (patch) | |
tree | 3e75e6f59047bb967c52915e1e75aee6ad67c0ea /caddyconfig/caddyfile/dispenser.go | |
parent | 42f75a4ca94ef3fb5e15a74e5dc9ef8b4f1f0b39 (diff) | |
parent | b2aa679c33f63ebec5bc1a21bca01f345dffebdd (diff) |
Merge pull request #2699 from caddyserver/cfadapter
v2: Implement config adapters and WIP Caddyfile adapter
Diffstat (limited to 'caddyconfig/caddyfile/dispenser.go')
-rwxr-xr-x | caddyconfig/caddyfile/dispenser.go | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/caddyconfig/caddyfile/dispenser.go b/caddyconfig/caddyfile/dispenser.go new file mode 100755 index 0000000..0d2c789 --- /dev/null +++ b/caddyconfig/caddyfile/dispenser.go @@ -0,0 +1,341 @@ +// Copyright 2015 Matthew Holt and The Caddy Authors +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package caddyfile + +import ( + "errors" + "fmt" + "strings" +) + +// Dispenser is a type that dispenses tokens, similarly to a lexer, +// except that it can do so with some notion of structure. An empty +// Dispenser is invalid; call NewDispenser to make a proper instance. +type Dispenser struct { + filename string + tokens []Token + cursor int + nesting int +} + +// NewDispenser returns a Dispenser filled with the given tokens. +// TODO: Get rid of the filename argument; it seems pointless here +func NewDispenser(filename string, tokens []Token) *Dispenser { + return &Dispenser{ + filename: filename, + tokens: tokens, + cursor: -1, + } +} + +// Next loads the next token. Returns true if a token +// was loaded; false otherwise. If false, all tokens +// have been consumed. +func (d *Dispenser) Next() bool { + if d.cursor < len(d.tokens)-1 { + d.cursor++ + return true + } + return false +} + +// Prev moves to the previous token. It does the inverse +// of Next(), except this function may decrement the cursor +// to -1 so that the next call to Next() points to the +// first token; this allows dispensing to "start over". This +// method returns true if the cursor ends up pointing to a +// valid token. +func (d *Dispenser) Prev() bool { + if d.cursor > -1 { + d.cursor-- + return d.cursor > -1 + } + return false +} + +// NextArg loads the next token if it is on the same +// line and if it is not a block opening (open curly +// brace). Returns true if an argument token was +// loaded; false otherwise. If false, all tokens on +// the line have been consumed except for potentially +// a block opening. It handles imported tokens +// correctly. +func (d *Dispenser) NextArg() bool { + if !d.nextOnSameLine() { + return false + } + if d.Val() == "{" { + // roll back; a block opening is not an argument + d.cursor-- + return false + } + return true +} + +// nextOnSameLine advances the cursor if the next +// token is on the same line of the same file. +func (d *Dispenser) nextOnSameLine() bool { + if d.cursor < 0 { + d.cursor++ + return true + } + if d.cursor >= len(d.tokens) { + return false + } + if d.cursor < len(d.tokens)-1 && + d.tokens[d.cursor].File == d.tokens[d.cursor+1].File && + d.tokens[d.cursor].Line+d.numLineBreaks(d.cursor) == d.tokens[d.cursor+1].Line { + d.cursor++ + return true + } + return false +} + +// NextLine loads the next token only if it is not on the same +// line as the current token, and returns true if a token was +// loaded; false otherwise. If false, there is not another token +// or it is on the same line. It handles imported tokens correctly. +func (d *Dispenser) NextLine() bool { + if d.cursor < 0 { + d.cursor++ + return true + } + if d.cursor >= len(d.tokens) { + return false + } + if d.cursor < len(d.tokens)-1 && + (d.tokens[d.cursor].File != d.tokens[d.cursor+1].File || + d.tokens[d.cursor].Line+d.numLineBreaks(d.cursor) < d.tokens[d.cursor+1].Line) { + d.cursor++ + return true + } + return false +} + +// NextBlock can be used as the condition of a for loop +// to load the next token as long as it opens a block or +// is already in a block. It returns true if a token was +// loaded, or false when the block's closing curly brace +// was loaded and thus the block ended. Nested blocks are +// not supported. +func (d *Dispenser) NextBlock() bool { + if d.nesting > 0 { + d.Next() + if d.Val() == "}" { + d.nesting-- + return false + } + return true + } + if !d.nextOnSameLine() { // block must open on same line + return false + } + if d.Val() != "{" { + d.cursor-- // roll back if not opening brace + return false + } + d.Next() + if d.Val() == "}" { + // open and then closed right away + return false + } + d.nesting++ + return true +} + +// Nested returns true if the token is currently nested +// inside a block (i.e. an open curly brace was consumed). +func (d *Dispenser) Nested() bool { + return d.nesting > 0 +} + +// Val gets the text of the current token. If there is no token +// loaded, it returns empty string. +func (d *Dispenser) Val() string { + if d.cursor < 0 || d.cursor >= len(d.tokens) { + return "" + } + return d.tokens[d.cursor].Text +} + +// Line gets the line number of the current token. If there is no token +// loaded, it returns 0. +func (d *Dispenser) Line() int { + if d.cursor < 0 || d.cursor >= len(d.tokens) { + return 0 + } + return d.tokens[d.cursor].Line +} + +// File gets the filename of the current token. If there is no token loaded, +// it returns the filename originally given when parsing started. +func (d *Dispenser) File() string { + if d.cursor < 0 || d.cursor >= len(d.tokens) { + return d.filename + } + if tokenFilename := d.tokens[d.cursor].File; tokenFilename != "" { + return tokenFilename + } + return d.filename +} + +// Args is a convenience function that loads the next arguments +// (tokens on the same line) into an arbitrary number of strings +// pointed to in targets. If there are fewer tokens available +// than string pointers, the remaining strings will not be changed +// and false will be returned. If there were enough tokens available +// to fill the arguments, then true will be returned. +func (d *Dispenser) Args(targets ...*string) bool { + for i := 0; i < len(targets); i++ { + if !d.NextArg() { + return false + } + *targets[i] = d.Val() + } + return true +} + +// RemainingArgs loads any more arguments (tokens on the same line) +// into a slice and returns them. Open curly brace tokens also indicate +// the end of arguments, and the curly brace is not included in +// the return value nor is it loaded. +func (d *Dispenser) RemainingArgs() []string { + var args []string + for d.NextArg() { + args = append(args, d.Val()) + } + return args +} + +// NewFromNextTokens returns a new dispenser with a copy of +// the tokens from the current token until the end of the +// "directive" whether that be to the end of the line or +// the end of a block that starts at the end of the line. +func (d *Dispenser) NewFromNextTokens() *Dispenser { + tkns := []Token{d.Token()} + for d.NextArg() { + tkns = append(tkns, d.Token()) + } + if d.Next() && d.Val() == "{" { + tkns = append(tkns, d.Token()) + for d.NextBlock() { + for d.Nested() { + tkns = append(tkns, d.Token()) + d.NextBlock() + } + } + tkns = append(tkns, d.Token()) + } else { + d.cursor-- + } + return NewDispenser(d.filename, tkns) +} + +// Token returns the current token. +func (d *Dispenser) Token() Token { + return d.TokenAt(d.cursor) +} + +func (d *Dispenser) TokenAt(cursor int) Token { + if cursor < 0 || cursor >= len(d.tokens) { + return Token{} + } + return d.tokens[cursor] +} + +// Cursor returns the current cursor (token index). +func (d *Dispenser) Cursor() int { + return d.cursor +} + +func (d *Dispenser) Reset() { + d.cursor = -1 +} + +// ArgErr returns an argument error, meaning that another +// argument was expected but not found. In other words, +// a line break or open curly brace was encountered instead of +// an argument. +func (d *Dispenser) ArgErr() error { + if d.Val() == "{" { + return d.Err("Unexpected token '{', expecting argument") + } + return d.Errf("Wrong argument count or unexpected line ending after '%s'", d.Val()) +} + +// SyntaxErr creates a generic syntax error which explains what was +// found and what was expected. +func (d *Dispenser) SyntaxErr(expected string) error { + msg := fmt.Sprintf("%s:%d - Syntax error: Unexpected token '%s', expecting '%s'", d.File(), d.Line(), d.Val(), expected) + return errors.New(msg) +} + +// EOFErr returns an error indicating that the dispenser reached +// the end of the input when searching for the next token. +func (d *Dispenser) EOFErr() error { + return d.Errf("Unexpected EOF") +} + +// Err generates a custom parse-time error with a message of msg. +func (d *Dispenser) Err(msg string) error { + msg = fmt.Sprintf("%s:%d - Error during parsing: %s", d.File(), d.Line(), msg) + return errors.New(msg) +} + +// Errf is like Err, but for formatted error messages +func (d *Dispenser) Errf(format string, args ...interface{}) error { + return d.Err(fmt.Sprintf(format, args...)) +} + +// Delete deletes the current token and returns the updated slice +// of tokens. The cursor is not advanced to the next token. +// Because deletion modifies the underlying slice, this method +// should only be called if you have access to the original slice +// of tokens and/or are using the slice of tokens outside this +// Dispenser instance. If you do not re-assign the slice with the +// return value of this method, inconsistencies in the token +// array will become apparent (or worse, hide from you like they +// did me for 3 and a half freaking hours late one night). +func (d *Dispenser) Delete() []Token { + if d.cursor >= 0 && d.cursor < len(d.tokens)-1 { + d.tokens = append(d.tokens[:d.cursor], d.tokens[d.cursor+1:]...) + d.cursor-- + } + return d.tokens +} + +// numLineBreaks counts how many line breaks are in the token +// value given by the token index tknIdx. It returns 0 if the +// token does not exist or there are no line breaks. +func (d *Dispenser) numLineBreaks(tknIdx int) int { + if tknIdx < 0 || tknIdx >= len(d.tokens) { + return 0 + } + return strings.Count(d.tokens[tknIdx].Text, "\n") +} + +// isNewLine determines whether the current token is on a different +// line (higher line number) than the previous token. It handles imported +// tokens correctly. If there isn't a previous token, it returns true. +func (d *Dispenser) isNewLine() bool { + if d.cursor < 1 { + return true + } + if d.cursor > len(d.tokens)-1 { + return false + } + return d.tokens[d.cursor-1].File != d.tokens[d.cursor].File || + d.tokens[d.cursor-1].Line+d.numLineBreaks(d.cursor-1) < d.tokens[d.cursor].Line +} |