1 files changed, 22 insertions, 0 deletions
diff --git a/src/js/mapvalues.js b/src/js/mapvalues.js
new file mode 100644
index 0000000..f701ba2
--- /dev/null
+++ b/src/js/mapvalues.js
@@ -0,0 +1,22 @@
+// reads the values of a machine map from its memmap.h. the #define lines may use
+// other names and small sums (ZFP + 2, DSLO + 1100), so each value is evaluated
+// with its names substituted. shared by extract_genome.js and extract_lsp.js.
+const fs = require('fs');
+
+function mapValues(mapPath, names) {
+    const text = fs.readFileSync(mapPath, 'utf8');
+    const defs = {};
+    for (const m of text.matchAll(/^#define[ \t]+(\w+)[ \t]+(.+)$/gm)) defs[m[1]] = m[2].trim();
+    function value(name, depth = 0) {
+        if (depth > 20) throw new Error('map loop at ' + name);
+        const expr = defs[name];
+        if (expr === undefined) throw new Error(mapPath + ' has no ' + name);
+        const sub = expr.replace(/\b[A-Za-z_]\w*\b/g, id => '(' + value(id, depth + 1) + ')');
+        return Function('return (' + sub + ');')();
+    }
+    const out = {};
+    for (const k of names) out[k] = value(k);
+    return out;
+}
+
+module.exports = { mapValues };