feat(grammar): add llama3.1 schema (#3015)

* wip

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* get rid of panics

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* expose it properly from the config

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Simplify

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* forgot to commit

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Remove focus on test

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

* Small fixups

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

---------

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

pkg/functions/grammars/rules.go

@@ -0,0 +1,93 @@
+package grammars
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/mudler/LocalAI/pkg/utils"
+)
+
+type Rules map[string]string
+
+func (rules Rules) ToGrammar(options ...func(*GrammarOption)) string {
+	grammarOpts := &GrammarOption{}
+	grammarOpts.Apply(options...)
+
+	prefix := grammarOpts.Prefix
+	maybeArray := grammarOpts.MaybeArray
+	disableParallelNewLines := grammarOpts.DisableParallelNewLines
+	maybeString := grammarOpts.MaybeString
+	noMixedFreeString := grammarOpts.NoMixedFreeString
+
+	var lines []string
+
+	swapRoot := maybeArray || maybeString || prefix != ""
+
+	// write down the computed rules.
+	// if maybeArray is true, we need to add the array rule and slightly tweak the root rule
+	for name, rule := range rules {
+		if swapRoot && name == "root" {
+			name = "realvalue"
+		}
+		lines = append(lines, fmt.Sprintf("%s ::= %s", name, rule))
+	}
+
+	if !swapRoot {
+		return strings.Join(lines, "\n")
+	}
+
+	newRoot := "realvalue"
+	if maybeArray {
+		newRoot = "arr | realvalue"
+	}
+
+	freestringRule := "mixedstring"
+	if noMixedFreeString {
+		freestringRule = "freestring"
+	}
+
+	if prefix != "" {
+		// quote newlines in suffix
+		prefix = utils.EscapeNewLines(prefix)
+
+		if maybeArray && maybeString {
+			newRoot = "(" + newRoot + ")"
+		}
+
+		if maybeString {
+			//newRoot = "( (\"" + suffix + "\" " + newRoot + ") | freestring ) "
+			newRoot = "( \"" + prefix + "\" " + newRoot + " | " + freestringRule + " ) "
+		} else {
+			newRoot = "\"" + prefix + "\" " + "" + newRoot + ""
+		}
+	} else if maybeString {
+		if maybeArray {
+			//	newRoot = "(" + newRoot + ")"
+		}
+
+		newRoot = freestringRule + " | " + newRoot
+	}
+
+	lines = append(lines, fmt.Sprintf("%s ::= %s", "root", newRoot))
+	if disableParallelNewLines {
+		lines = append(lines, array)
+	} else {
+		lines = append(lines, arrayNewLines)
+	}
+
+	if maybeArray {
+		if grammarOpts.ExpectStringsAfterJSON {
+			lines = append(lines, `mixedstring ::= freestring | freestring arr freestring | (freestring realvalue freestring)* | realvalue | arr`)
+		} else {
+			lines = append(lines, `mixedstring ::= freestring | freestring arr | freestring realvalue | realvalue | arr`)
+		}
+	} else {
+		if grammarOpts.ExpectStringsAfterJSON {
+			lines = append(lines, `mixedstring ::= freestring | (freestring realvalue freestring)* | realvalue`)
+		} else {
+			lines = append(lines, `mixedstring ::= freestring | freestring realvalue | realvalue`)
+		}
+	}
+
+	return strings.Join(lines, "\n")
+}