chore(deps): bump chroma to v2 #735

Bump `alecthomas/chroma` to `v2`:
https://github.com/cheat/cheat/issues/735

vendor/github.com/alecthomas/chroma/v2/mutators.go

@@ -0,0 +1,201 @@
+package chroma
+
+import (
+	"encoding/xml"
+	"fmt"
+	"strings"
+)
+
+// A Mutator modifies the behaviour of the lexer.
+type Mutator interface {
+	// Mutate the lexer state machine as it is processing.
+	Mutate(state *LexerState) error
+}
+
+// SerialisableMutator is a Mutator that can be serialised and deserialised.
+type SerialisableMutator interface {
+	Mutator
+	MutatorKind() string
+}
+
+// A LexerMutator is an additional interface that a Mutator can implement
+// to modify the lexer when it is compiled.
+type LexerMutator interface {
+	// MutateLexer can be implemented to mutate the lexer itself.
+	//
+	// Rules are the lexer rules, state is the state key for the rule the mutator is associated with.
+	MutateLexer(rules CompiledRules, state string, rule int) error
+}
+
+// A MutatorFunc is a Mutator that mutates the lexer state machine as it is processing.
+type MutatorFunc func(state *LexerState) error
+
+func (m MutatorFunc) Mutate(state *LexerState) error { return m(state) } // nolint
+
+type multiMutator struct {
+	Mutators []Mutator `xml:"mutator"`
+}
+
+func (m *multiMutator) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	for {
+		token, err := d.Token()
+		if err != nil {
+			return err
+		}
+		switch token := token.(type) {
+		case xml.StartElement:
+			mutator, err := unmarshalMutator(d, token)
+			if err != nil {
+				return err
+			}
+			m.Mutators = append(m.Mutators, mutator)
+
+		case xml.EndElement:
+			return nil
+		}
+	}
+}
+
+func (m *multiMutator) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	name := xml.Name{Local: "mutators"}
+	if err := e.EncodeToken(xml.StartElement{Name: name}); err != nil {
+		return err
+	}
+	for _, m := range m.Mutators {
+		if err := marshalMutator(e, m); err != nil {
+			return err
+		}
+	}
+	return e.EncodeToken(xml.EndElement{Name: name})
+}
+
+func (m *multiMutator) MutatorKind() string { return "mutators" }
+
+func (m *multiMutator) Mutate(state *LexerState) error {
+	for _, modifier := range m.Mutators {
+		if err := modifier.Mutate(state); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Mutators applies a set of Mutators in order.
+func Mutators(modifiers ...Mutator) Mutator {
+	return &multiMutator{modifiers}
+}
+
+type includeMutator struct {
+	State string `xml:"state,attr"`
+}
+
+// Include the given state.
+func Include(state string) Rule {
+	return Rule{Mutator: &includeMutator{state}}
+}
+
+func (i *includeMutator) MutatorKind() string { return "include" }
+
+func (i *includeMutator) Mutate(s *LexerState) error {
+	return fmt.Errorf("should never reach here Include(%q)", i.State)
+}
+
+func (i *includeMutator) MutateLexer(rules CompiledRules, state string, rule int) error {
+	includedRules, ok := rules[i.State]
+	if !ok {
+		return fmt.Errorf("invalid include state %q", i.State)
+	}
+	rules[state] = append(rules[state][:rule], append(includedRules, rules[state][rule+1:]...)...)
+	return nil
+}
+
+type combinedMutator struct {
+	States []string `xml:"state,attr"`
+}
+
+func (c *combinedMutator) MutatorKind() string { return "combined" }
+
+// Combined creates a new anonymous state from the given states, and pushes that state.
+func Combined(states ...string) Mutator {
+	return &combinedMutator{states}
+}
+
+func (c *combinedMutator) Mutate(s *LexerState) error {
+	return fmt.Errorf("should never reach here Combined(%v)", c.States)
+}
+
+func (c *combinedMutator) MutateLexer(rules CompiledRules, state string, rule int) error {
+	name := "__combined_" + strings.Join(c.States, "__")
+	if _, ok := rules[name]; !ok {
+		combined := []*CompiledRule{}
+		for _, state := range c.States {
+			rules, ok := rules[state]
+			if !ok {
+				return fmt.Errorf("invalid combine state %q", state)
+			}
+			combined = append(combined, rules...)
+		}
+		rules[name] = combined
+	}
+	rules[state][rule].Mutator = Push(name)
+	return nil
+}
+
+type pushMutator struct {
+	States []string `xml:"state,attr"`
+}
+
+func (p *pushMutator) MutatorKind() string { return "push" }
+
+func (p *pushMutator) Mutate(s *LexerState) error {
+	if len(p.States) == 0 {
+		s.Stack = append(s.Stack, s.State)
+	} else {
+		for _, state := range p.States {
+			if state == "#pop" {
+				s.Stack = s.Stack[:len(s.Stack)-1]
+			} else {
+				s.Stack = append(s.Stack, state)
+			}
+		}
+	}
+	return nil
+}
+
+// Push states onto the stack.
+func Push(states ...string) Mutator {
+	return &pushMutator{states}
+}
+
+type popMutator struct {
+	Depth int `xml:"depth,attr"`
+}
+
+func (p *popMutator) MutatorKind() string { return "pop" }
+
+func (p *popMutator) Mutate(state *LexerState) error {
+	if len(state.Stack) == 0 {
+		return fmt.Errorf("nothing to pop")
+	}
+	state.Stack = state.Stack[:len(state.Stack)-p.Depth]
+	return nil
+}
+
+// Pop state from the stack when rule matches.
+func Pop(n int) Mutator {
+	return &popMutator{n}
+}
+
+// Default returns a Rule that applies a set of Mutators.
+func Default(mutators ...Mutator) Rule {
+	return Rule{Mutator: Mutators(mutators...)}
+}
+
+// Stringify returns the raw string for a set of tokens.
+func Stringify(tokens ...Token) string {
+	out := []string{}
+	for _, t := range tokens {
+		out = append(out, t.Value)
+	}
+	return strings.Join(out, "")
+}