From ca074ce38774499d6e1b47799450f6ab30a06d6c Mon Sep 17 00:00:00 2001
From: Dietrich Epp <depp@zdome.net>
Date: Tue, 15 Mar 2022 14:31:12 -0400
Subject: [PATCH] Write conversion from script and region to charmap

The generation tool creates a GetCharmap function in C which takes the
script and region as input and returns the charmap index.
---
 gen/main.go      |   7 ++-
 gen/scriptmap.go | 133 +++++++++++++++++++++++++++++++++++++++++++++++
 src/.gitignore   |   1 +
 3 files changed, 140 insertions(+), 1 deletion(-)
 create mode 100644 gen/scriptmap.go
 create mode 100644 src/.gitignore

diff --git a/gen/main.go b/gen/main.go
index e06aded..e66ab9c 100644
--- a/gen/main.go
+++ b/gen/main.go
@@ -7,6 +7,8 @@ import (
 	"path/filepath"
 )
 
+const header = "/* This file is automatically generated. */\n"
+
 var (
 	flagDumpSequences   bool
 	flagDumpTransitions bool
@@ -37,7 +39,10 @@ func mainE() error {
 	if err != nil {
 		return err
 	}
-	_ = d
+	m := genMap(&d)
+	if err := writeMap(&d, m, "src/getcharmap.c"); err != nil {
+		return err
+	}
 	return nil
 }
 
diff --git a/gen/scriptmap.go b/gen/scriptmap.go
new file mode 100644
index 0000000..b44c545
--- /dev/null
+++ b/gen/scriptmap.go
@@ -0,0 +1,133 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"os/exec"
+	"sort"
+)
+
+type regionmap struct {
+	regions []int
+	charmap int
+}
+
+type regionmaps []regionmap
+
+func (s regionmaps) Len() int      { return len(s) }
+func (s regionmaps) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s regionmaps) Less(i, j int) bool {
+	x := s[i]
+	y := s[j]
+	switch {
+	case len(y.regions) == 0:
+		return true
+	case len(x.regions) == 0:
+		return false
+	default:
+		return x.regions[0] < y.regions[0]
+	}
+}
+
+type scriptmap struct {
+	script  int
+	regions []regionmap
+}
+
+type scriptmaps []*scriptmap
+
+func (s scriptmaps) Len() int           { return len(s) }
+func (s scriptmaps) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s scriptmaps) Less(i, j int) bool { return s[i].script < s[j].script }
+
+// genMap generates a map from scripts and regions to charmaps.
+func genMap(d *scriptdata) []*scriptmap {
+	m := make(map[int]*scriptmap)
+	var r []*scriptmap
+	for i, cm := range d.charmaps {
+		s := m[cm.script]
+		if s == nil {
+			s = &scriptmap{script: cm.script}
+			m[cm.script] = s
+			r = append(r, s)
+		}
+		var rgs []int
+		if len(cm.regions) != 0 {
+			rgs = make([]int, len(cm.regions))
+			copy(rgs, cm.regions)
+			sort.Ints(rgs)
+		}
+		s.regions = append(s.regions, regionmap{
+			regions: cm.regions,
+			charmap: i,
+		})
+	}
+	for _, s := range r {
+		sort.Sort(regionmaps(s.regions))
+	}
+	sort.Sort(scriptmaps(r))
+	return r
+}
+
+// writeMap writes out a C function that returns the correct character map for a
+// given script and region.
+func writeMap(d *scriptdata, m []*scriptmap, filename string) error {
+	fmt.Fprintln(os.Stderr, "Writing:", filename)
+
+	fp, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer fp.Close()
+	w := bufio.NewWriter(fp)
+
+	w.WriteString(header)
+	w.WriteString(
+		"int GetCharmap(int script, int region) {\n" +
+			"switch (script) {\n")
+	for _, s := range m {
+		fmt.Fprintf(w, "case %d: /* %s */\n", s.script, d.scripts.values[s.script])
+		if len(s.regions) == 1 && len(s.regions[0].regions) == 0 {
+			r := s.regions[0]
+			fmt.Fprintf(w, "return %d; /* %s */\n", r.charmap, d.charmaps[r.charmap].name)
+		} else {
+			w.WriteString("switch (region) {\n")
+			var hasdefault bool
+			for _, r := range s.regions {
+				if len(r.regions) == 0 {
+					w.WriteString("default:\n")
+					hasdefault = true
+				} else {
+					for _, rg := range r.regions {
+						fmt.Fprintf(w, "case %d: /* %s */\n", rg, d.regions.values[rg])
+					}
+				}
+				fmt.Fprintf(w, "return %d; /* %s */\n", r.charmap, d.charmaps[r.charmap].name)
+			}
+			if !hasdefault {
+				w.WriteString("default:\nreturn -1;\n")
+			}
+			w.WriteString("}\n")
+		}
+	}
+	w.WriteString(
+		"default:\n" +
+			"return -1;\n" +
+			"}\n" +
+			"}\n")
+
+	if err := w.Flush(); err != nil {
+		return err
+	}
+	if err := fp.Close(); err != nil {
+		return err
+	}
+
+	cmd := exec.Command("clang-format", "-i", filename)
+	if err := cmd.Run(); err != nil {
+		fmt.Fprintln(os.Stderr, "Warning: clang-format failed:", err)
+	}
+
+	return nil
+}
diff --git a/src/.gitignore b/src/.gitignore
new file mode 100644
index 0000000..24c33a0
--- /dev/null
+++ b/src/.gitignore
@@ -0,0 +1 @@
+/getcharmap.c